THIL 


HOUS 


L.O.HOWARD 


••••••••IIHHMHI 


THE  HOUSE  FLY— DISEASE  CARRIER 


THE    HOUSE    FLY DISEASE    CARRIER 


THE 

HOUSE  FLY 

DISEASE   CARRIER 


AN    ACCOUNT    OF    ITS    DANGEROUS 

ACTIVITIES  AND  OF  THE  MEANS 

OF  DESTROYING  IT 


BY 

L.  O.  HOWARD,  PH.D. 


NEW  YORK 

FREDERICK  A.  STOKES  COMPANY 
PUBLISHERS 


Public  Health  Lib. 


Copyright,  1911,  by 
FREDERICK  A.  STOKES  COMPANY 

All  rights  reserved,  including  that  of  translation  into  foreign 
languages,  including  the  Scandinavian 


May,  1911 


Ft 


CONTENTS 

PAGE 

INTRODUCTION xv 

CHAPTER  I 

ZOOLOGICAL  POSITION,  LIFE  HISTORY,  AND  HABITS  i 

Life  History 6 

The  Egg  ...........  18 

The  Larva 19 

The  Pupa  and  Puparium 23 

Emergence  of  the  Adult 25 

Structure  of  the  Adult 27 

Difference  in  Size  of  Adults 32 

Summary  of  Duration  of  Life  Round     .      .  35 

Number  of  Generations 36 

Possibilities  in  the  Way  of  Numbers     .      .  37 
Number   by   Actual    Count    in    Relation    to 

Quantity  of  Food 39 

Hibernation 41 

Habits  of  the  Adult   Fly 44 

Do  Flies  have  a  Color  Preference?  ...  47 

Fly-Specks 48 

Distance  of  Flight 51 

Marking  Flies  for  Experiment     ....  56 

Length  of  Life  of  the  Adult 58 

Time  Elapsing  between  the  Iss'ning  of  the 

Adult  and  the  Period  of  Sexual  Maturity  60 
v 


M638258 


vi  CONTENTS 

CHAPTER  II 

PAGE 

THE  NATURAL  ENEMIES  OF  THE  TYPHOID  FLY     .  62 

Fungous  Diseases 62 

Protozoan  Enemies  of  the  House  Fly     .      .  70 

Nematode  Parasites  of  the  Typhoid  Fly     .      .  72 

The  Mite  Enemies  of  Musca  Domestica     .      .  75 

Spiders  as  Fly  Enemies 78 

False   Scorpions  on  Flies 80 

The  House  Centipede 82 

Insect  Enemies  of  the  House  Fly     ....  84 

Predatory  Enemies 84 

Parasitic  Enemies 88 

Vertebrate  House  Fly  Enemies 95 

Fly-Catching  Rats 97 

CHAPTER  III 

THE  CARRIAGE  OF  DISEASE  BY  FLIES     ....  100 

Exact  Experiments 102 

Typhoid  or  Enteric  Fever 112 

Suspicions  of  the  Carriage  of  Typhoid  by 

Flies 114 

Inferential  Proof 116 

Exact  Proof 125 

Chronic  Carriers 128 

Influence  of  Flies  in  the  Carriage  of  Typhoid 

in  Cities 138 

Other  Points .148 

Cholera 150 

Dysentery 155 

Diarrhea  in  Infants 156 

Tuberculosis                                  162 


CONTENTS  vii 


PAGE 


Anthrax 164 

Yaws  (FrambcKsia  tropica) 165 

Ophthalmia 167 

Diphtheria 170 

Small-pox 170 

Plague 171 

Tropical  Sore 172 

Parasitic  Worms 173 

CHAPTER  IV 

REMEDIES  AND  PREVENTIVE  MEASURES  ....  175 

Screening 177 

Fly  Traps  and  Fly  Poisons 178 

Formalin 185 

Pyrethrum  and  Carbolic  Acid 188 

Repellents 189 

Search  for  Breeding  Places 190 

The  Treatment  of  Horse  Manure  ....  193 
Removal  of  Manure  and  Receptacles  for  Its 

Temporary  Storage 201 

The  Sanitary  Privy .  203 

A  Compulsory  Sanitary  Privy  Law  .  .  .  210 

The  Capture  of  Adult  Flies  Outside  of  Houses  212 

Special  Considerations  for  Towns  and  Cities  .  217 

Organization 218 

•  Interesting  the  Children  .  .  .  .  .  .  224 

Boards  of  Health 230 

Army  Camps 233 

CHAPTER  V 

OTHER  FLIES  FREQUENTING  HOUSES  .  2i~ 

The  Cluster  Fly  (Pollenia  rudis  Fabr.)      .      .  236 


viii  CONTENTS 

PACK 

The  Biting  House  Fly  (Stomoxys  calcitrant  L.)  240 
The  Little  House  Fly  (Fannia  [Homalomyia] 

canicularis  L.)     .          246 

The  Stable  Fly  (Muscina  stabnlans  Fall.)      .  248 

The  Cheese  Fly  (Piophila  casci  L.)      .      .      .  249 
The  Fruit  Flies  (Drosophila  ampclophila  Loevv.)  251 

The  Bluebottle  or  Greenbottle  Flies     ...  252 
The    Blow    Flies    (Calliphora    crythroccphala 
Meig.,  Lucilia  cccsar  L.,  Phormia  terrccno- 

v<£  Desv.) 252 

The  Flesh  Flies   (Sarcophaga  assidua  Walk.)  254 
The  Dung  Flies   (Sepsis  riolacea  Meig.,  Sca- 

tophaga  furcata  Say.) 255 

The  Moth  Flies  (Psychoda  minuta  Banks.)      .  256 

The  Humpback  Flies 257 

The  Window  Flies  (Scenopimis  fcnestralis  L.)  258 

BIBLIOGRAPHICAL  LIST ' .      .261 

APPENDIX  I 273 

APPENDIX  II 281 

APPENDIX  III 285 

APPENDIX  IV 293 

APPENDIX  V 3°5 


ILLUSTRATIONS 

The  house  fly — Disease  carrier       .      .      .     Frontispiece 

FIG.  PACK 

1.  Eggs,  approximately  natural  size;  photographed 

on    surface    of    manure    pile    (from    New- 
stead)     facing       18 

2.  Eggs,  approximately  natural  size  (from  New- 

stead)     facing       18 

3.  Eggs,  greatly  enlarged  (from  Newstead)  facing       20 

4.  Eggs,   greatly   enlarged — another   view    (from 

Newstead) facing  20 

5.  Egg  of  house  fly;  greatly  enlarged  ....  19 

6.  Egg  hatching;  greatly  enlarged      .      .     facing  22 

7.  Full   grown   larva   of    house    fly;   greatly    en- 

larged      facing       22 

8.  Larvae  in  horse  manure  (from  Newstead)  facing       24 

9.  Larvae  and  puparia  (from  Newstead)    .   facing       24 

10.  Puparia  on  a  bit  of  old  rotting  cloth  from  an 

ash  barrel  (from  Newstead)      .      .     facing      26 

11.  House  fly  puparium  and  pupa;  greatly  enlarged      24 

12.  Adult    house    fly    from    above;    greatly    en- 

larged      facing      28 

13.  Adult    house    fly    from    below;    greatly    en- 

larged      facing      28 

14.  Head  of  adult  house  fly ;  greatly  enlarged  facing      30 

15.  Head  of  adult  house  fly  from  side;  greatly  en- 

larged      facing      30 


x  LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

1 6.  A  diagrammatic  figure  of  the  alimentary  canal 

of  the  house  fly;  greatly  enlarged     ...       29 

17.  The  house  centipede  (Scutigera  forceps)  ;  some- 

what enlarged  (after  Marlatt)    .      .     facing       82 

1 8.  Colonies  of  bacteria  on  a  sterilized  plate,  aris- 

ing from  fly  tracks facing  108 

19.  Details  of  window  trap  (redrawn  from  Parrott)  181 

20.  Fly  trap  for  garbage  can     ....     facing  214 

21.  Poster  issued  by  the  Florida  State  Board  of 

Health ;  greatly  reduced  ....     facing     224 

22.  The  cluster  fly    (Pollcnia   rudis)  ;  greatly  en- 

larged      facing     238 

23.  The   biting  house  fly    (Stomo.vys   calcitrant)  ; 

greatly  enlarged facing     238 

24.  The    little    house    fly    (Homalomyia    breris)  ; 

greatly   enlarged facing     246 

25.  The  stable  fly  (Muscina  stabulans)  ;  greatly  en- 

larged      facing     246 

26.  The  cheese  fly  (Piophila  casei)  ;  enlarged  facing     250 

27.  The   fruit   fly    (Drosophila   ampclophila)  \  en- 

larged      facing  250 

28.  Lucilia  ccesar ;  enlarged facing  254 

29.  Calliphora  erythrocephala;  enlarged    .     facing  254 

30.  Phormia  tcrrcenovcc  ;  enlarged   .      .      .     facing  254 

31.  Sarcophaga  assidua;  enlarged  .      .      .     facing  256 

32.  Sepsis  violacea;  enlarged     ....     facing  256 

33.  Scatophaga  fnrcata;  enlarged   .      .      .     facing  254 

34.  Phora  femorata;  enlarged  greatly     ....  257 

35.  Scenopinns  fencstralis;  enlarged 258 

36.  Scantling  for  framework  of  single-seated  privy 

(Redrawn  from  Stiles) 295 

37.  The  framework  for  a  single-seated  privy  (Re- 

drawn from  Stiles) 297 


LIST  OF  ILLUSTRATIONS  xi 

"G-  PAGE 

38.  Front  view  of  single-seated  sanitary  privy  (Re- 

drawn from  Stiles) 299 

39.  Rear  view  of  single-seated  sanitary  privy  (Re- 

drawn from  Stiles) 301 

40.  The  Lumsden,  Roberts  and  Stiles  apparatus  for 

the  safe  disposal  of  night-soil  (Redrawn  from 
Lumsden,  Roberts  and  Stiles)      ....     307 


INTRODUCTION 


INTRODUCTION 

IT  is  only  within  the  last  twelve  years  that  the  dan- 
gerous character  of  the  common  house  fly  has  been 
known;  and  only  within  the  last  two  years  have  the 
people  at  large  begun  to  wake  up  to  this  danger  and 
to  inquire  concerning  the  means  by  which  this  fly  can 
be  kept  down.  The  writer  published  some  account 
of  its  life  history  in  a  bulletin  on  household  insects 
published  by  the  U.  S.  Department  of  Agriculture  in 
1896.  Later  he  made  some  experiments  with  regard 
to  remedies,  and  in  1900  published  a  rather  lengthy 
paper  on  the  insect  fauna  of  human  excrement  with 
especial  reference  to  the  carriage  of  typhoid  fever  by 
flies.  Within  the  last  two  years,  however,  articles 
relating  to  the  so-called  house  fly  in  connection  with 
its  disease-carrying  possibilities  have  been  published 
literally  by  the  thousand,  and  this  interest,  perhaps 
having  its  origin  in  the  United  States,  has  spread  to 
nearly  all  parts  of  the  civilized  world,  and  yet  in  no 
one  of  these  published  articles  is  the  .whole  story  told. 
No  one  can  find  in  condensed  and  convenient  shape 
the  general  information  he  desires  in  regard  to  this 
insect.  The  publishers  of  this  book,  realizing  this  fact, 
have  invited  the  author  to  attempt  to  fill  this  want. 

This  book  is  not  intended  to  be  a  scientific  mono- 
graph ;  it  is  simply  an  attempt  to  tell  in  an  understand- 
able way  what  is  known  about  the  subjects  indicated 
in  the  title. 

xv 


xvi      THE  HOUSE  FLY— DISEASE  CARRIER 

And  mention  of  the  title  brings  up  the  point  as  to 
whether  the  writer  was  justified  when  he  proposed  the 
name  typhoid  fly  for  the  old  and  well-known  house 
fly  at  the  meeting  of  the  Committee  of  One  Hundred 
on  Public  Health  at  the  meeting  of  the  American  As- 
sociation for  the  Advancement  of  Science,  in  Baltimore, 
during  the  Christmas  week  in  1908.  He  has  been  crit- 
icized for  making  this  suggestion  by  the  Association 
of  Economic  Entomologists'  Committee  on  Popular 
Names  and  also  by  certain  medical  men.  The  objec- 
tions have  been  that  this  name  would  indicate  the  be- 
lief on  the  part  of  the  proposer  and  of  those  who  should 
subsequently  use  it  that  the  house  fly  is  the  sole  car- 
rier of  typhoid  or  that  it  is  the  principal  carrier  of  ty- 
phoid ;  in  other  words,  that  it  is  given  too  much  prom- 
inence from  the  standpoint  of  the  etiology  of  typhoid 
fever.  As  a  matter  of  fact,  however,  the  writer  never 
claimed  that  it  was  the  only  carrier  of  typhoid  or  that 
it  was  the  principal  carrier  of  typhoid  except  under 
certain  peculiar  conditions.  In  fact,  the  suggestion 
seems  to  him  to  have  been  quite  sufficiently  guarded. 
It  was  as  follows:  "The  name  'typhoid  fly'  is  here 
proposed  as  a  substitute  for  the  name  'house  fly'  now 
in  general  use.  People  have  altogether  too  long  con- 
sidered the  house  fly  as  a  harmless  creature,  or  at  the 
most  simply  a  nuisance.  While  scientific  researches 
have  shown  that  it  is  a  most  dangerous  creature  from 
the  standpoint  of  disease,  and  while  popular  opinion 
is  rapidly  being  educated  to  the  same  point,  the  re- 
tention of  the  name  'house  fly'  is  considered  inadvis- 


INTRODUCTION  xvii 

able  as  perpetuating  in  some  degree  the  old  ideas. 
Strictly  speaking,  .the  term  'typhoid  fly'  is  open  to  some 
objection  as  conveying  the  erroneous  idea  that  this  fly 
is  solely  responsible  for  the  spread  of  typhoid,  but, 
considering  that  the  creature  is  dangerous  from  every 
point  of  view  and  that  it  is  an  important  element  in 
the  spread  of  typhoid,  it  seems  advisable  to  give  it  a 
name  which  is  almost  wholly  justified  and  which  con- 
veys in  itself  the  idea  of  serious  disease.  Another 
repulsive  name  that  might  be  given  to  it  is  'manure 
fly/  but  recent  researches  have  shown  that  it  is  not 
confined  to  manure  as  a  breeding  place,  although  per- 
haps the  great  majority  of  these  flies  are  born  in  horse 
manure.  For  the  end  in  view,  'typhoid  fly'  is  consid- 
ered the  best  name." 

As  a  matter  of  fact  this  name  has  been  adopted  very 
generally.  The  newspapers  took  it  up  with  avidity, 
and  during  the  summers  of  1909  and  especially  of 
1910,  many  good  journals  conducted  a  constant  ed- 
itorial campaign,  almost  every  issue  during  the  sum- 
mer months  containing  some  reading  matter  calling 
attention  to  the  danger  of  the  creature  and  the  ne- 
cessity of  fighting  it.  It  is  undoubtedly  true  that  peo- 
ple will  fear  and  fight  an  insect  bearing  the  name  "ty- 
phoid fly"  when  they  will  ignore  one  called  the  "house 
fly,"  which  they  have  always  considered  a  harmless 
insect.  So  to  gain  the  practical  end  the  retention  of 
the  name  "typhoid  fly"  seems  by  all  means  to  be  ad- 
visable. The  only  substitute  suggested  in  the  two 
years  since  this  term  has  been  adopted  which  ap- 


xviii    THE  HOUSE  FLY— DISEASE  CARRIER 

preaches  it  for  suggestiveness  and  availability  is  the 
name  "filth  fly,"  proposed  by  Dr.  C.  W.  Stiles,  of  the 
U.  S.  Public  Health  and  Marine-Hospital  Service. 
But  "filth  fly,"  while  a  nauseating  name  associated  as 
it  must  be  with  the  dinner  tables  of  unscreened  houses, 
carries  simply  the  noisome  idea  and  not  the  dangerous 
idea,  and  the  latter  is  one  that  will  induce  people  to 
fight. 

It  will  not  be  an  easy  fight.  The  species  is  firmly 
intrenched;  it  multiplies  with  startling  rapidity,  and 
its  breeding  places  are  everywhere.  Improved  sanitary 
methods  in  cities  and  the  gradual  disappearance  in 
cities  of  horse  stables,  due  to  the  rapid  increase  in  the 
number  of  motor  vehicles,  are  bringing  about  a  de- 
cided lessening  of  the  myriads  of  flies  in  the  cities. 
In  small  towns,  however,  and  in  the  country  and  at 
army  posts,  and  especially  in  concentration  camps,  and 
wherever  large  bodies  of  men  are  brought  together 
for  temporary  purposes  in  construction  work,  there  is 
great  need  of  intimate  practical  knowledge  of  the  ty- 
phoid fly  and  of  the  measures  to  be  taken  against  it. 
The  residents  of  cities  must  also  have  this  knowledge, 
but  they  need  it  less  than  the  others. 

Acknowledgments  of  assistance  from  others  will 
be  made  in  the  text  from  time  to  time.  The  writer 
wishes  especially,  however,  to  thank  Prof.  S.  A.  Forbes, 
Dr.  C.  W.  Stiles,  and  Dr.  B.  H.  Ransom  for  allowing 
him  to  use  their  very  valuable  but  as  yet  unpublished 
notes  on  several  aspects  of  the  fly  question.  He  wishes 
also  to  thank  Mr.  R.  B.  Watrous,  Secretary  of  the 


INTRODUCTION  xix 

American  Civic  Association,  for  access  to  his  large 
correspondence  on  the  fly  crusade.  He  is  also  indebted 
to  Mr.  Gilbert  H.  Grosvenor,  editor  of  the  National 
Geographic  Magazine,  and  to  Mr.  Robert  Newstead, 
for  permission  to  use  certain  illustrations  which  will 
be  found  properly  accredited  in  the  text. 


The  House  Fly— Disease  Carrier 


ZOOLOGICAL  POSITION,  LIFE  HISTORY,  AND 
HABITS 

ZOOLOGICAL  POSITION 

'VOOLOGICALLY  speaking,  this  insect  belongs  to 
1-*  the  order  Diptera,  or  two-winged  flies.  In  this 
order  it  is  the  type  of  a  superfamily  known  as  the  Mus- 
coidea,  of  a  family  known  as  the  Muscidae  and  of  the 
genus  Musca,  the  specific  name  given  to  it  originally 
by  Linnaeus  being  domestica;  and  among  zoologists  it 
is  referred  to  as  Musca  domestica  L. 

The  superfamily  Muscoidea,  to  which  it  belongs  and 
of  which  it  is  the  type,  is  a  very  large  group  contain- 
ing a  number  of  families  and  many  species  which  so 
closely  resemble  the  house  fly  that  to  the  untrained  eye 
they  cannot  be  distinguished.  Dr.  David  Sharp,  in 
the  Cambridge  Natural  History,  writing  of  the  house 
fly,  states  that  "it  sometimes  occurs  in  large  numbers 
away  from  the  dwellings  of  man,"  and  the  writer  is 
often  asked  to  explain  why  parties  camping  in  the 
Northwest,  on  the  prairies  for  example,  many  miles 
away  from  human  habitations,  almost  immediately 
find  their  camps  infested  with  the  house  fly.  The  an- 
swer to  such  questions,  and  possibly  the  answer  to  the 


2      THE  HOUSE  FLY— DISEASE  CARRIER 

statement  made  by  Doctor  Sharp,  is  that  the  flies  found 
under  such  conditions  are  not  house  flies,  but  some 
species  closely  resembling  Musca  domcstica.  In  the 
family  Tachinidae,  a  group  composed  almost  entirely 
of  species  which  lay  their  eggs  upon  other  living  in- 
sects, there  are  many  species  which  almost  precisely 
resemble  the  gray-and-black-striped  house  fly.  In  the 
family  Dexidae,  of  similar  habits,  there  are  also  many 
which  closely  resemble  the  house  fly.  In  the  family 
Sarcophagidae,  which  includes  most  of  the  so-called 
flesh  flies,  the  species  of  which  either  live  in  carrion 
or  excreta  or  in  dead  insects  or  in  putrid  matter,  and 
are  occasionally  parasitic,  as  with  the  species  which 
breed  in  the  egg-masses  of  grasshoppers,  there  are  also 
many  species  hardly  to  ,be  distinguished  from  Musca. 
There  is  another  great  family,  the  Anthomyidae,  which 
has  many  species  which  closely  resemble  the  house 
fly  and  give  rise  to  many  mistakes  in  identity.  These 
insects  in  their  early  stages  feed  upon  decaying  vege- 
table matter  and  also  to  some  extent  upon  growing 
plants,  and  a  few  prey  upon  the  eggs  of  grasshoppers. 
Then,  too,  in  the  family  Muscidae  itself  there  are  many 
genera  of  similar  habits  and  similar  appearance.  The 
writer  once,  as  a  test,  selected  twenty  distinct  species 
from  among  these  insects  and  carefully  pinned  them 
into  a  tray,  asking  chance  visitors  for  several  weeks 
to  pick  out  the  true  house  flies  from  among  them.  No 
one  was  ever  able  to  distinguish  between  the  different 
forms  by  looking  at  them  with  the  naked  eye. 

The  habits  of  the  different  genera  of  Muscidae  are 


ZOOLOGICAL  POSITION  3 

rather  uniform,  except  that  with  a  few  of  them  the 
adults  bite  and  suck  blood,  while  the  majority,  like 
Musca  domestica,  do  not.  The  tsetse  flies  of  Africa, 
belonging  to  the  genus  Glossina,  bite,  as  also  do  the 
stable  flies  of  the  genus  Stomoxys  and  the  cattle  flies 
of  the  genus  Hsematobia  (this  genus  includes  the  so- 
called  horn  fly  of  cattle).  Of  the  other  genera,  Graph- 
omyia,  Morellia,  Mesembrina,  Pyrellia,  Pseudopyrel- 
lia,  and  Phormia  all  breed  in  excrementitious  matter. 
The  genus  Myospila,  formerly  placed  in  the  Muscidse 
but  really  anthomyid,  is  also  a  breeder  in  this  material. 
The  flies  of  the  genus  Muscina  breed  in  decaying  vege- 
tation and  in  cow  dung,  as  also  do  those  of  the  genus 
Pollenia.  Those  of  the  genus  Cynomyia  and  of  the 
genus  Calliphora  and  of  the  genus  Lucilia  breed  in 
dead  animal  matter,  while  Chrysomyia  inacellaria — 
the  famous  screw-worm  fly — breeds  in  living  flesh. 

Some  of  these  flies  are  occasionally  found  in  houses, 
and  further  consideration  of  them  will  be  found  in 
Chapter  V.  For  practical  purposes  they  are  all  equally 
dangerous,  as  possible  disease  carriers,  and  to  the  prac- 
tical person  there  is  no  especial  need  to  distinguish 
among  them ;  but  fortunately  the  house  fly  is  the  only 
one  that  comes  in  abundance  to  houses.  It  is  the  only 
one  which  really  deserves  the  term  domestic. 

For  the  two  following  paragraphs,  which  indicate 
the  easiest  method  of  distinguishing  the  house  fly  from 
any  of  its  allies,  I  am  indebted  to  Mr.  D.  W.  Coquil- 
lett,  an  authority  on  the  order  Diptera : 

"From  nearly  all  the  other  kinds  of  flies  that  resem- 


4      THE  HOUSE  FLY— DISEASE  CARRIER 

ble  it,  the  house  fly  can  be  distinguished  by  having  no 
bristles  on  the  sides  of  the  thorax  above  the  attach- 
ment of  the  last  pair  of  legs  and  by  having  the  vein 
that  ends  near  the  tip  of  the  wing  distinctly  elbowed, 
a  short  distance  before  its  apex.  Several  different 
kinds  of  Tachinidae,  Dexidae  and  Sarcophagidre  have 
a  superficial  resemblance  to  the  house  fly,  and,  like  it, 
have  the  elbowed  vein,  but  all  of  them  differ  from  the 
house  fly  in  possessing  a  row  of  bristles  above  the 
point  of  attachment  of  the  last  pair  of  legs.  The  only 
other  family  containing  species  that  might  be  mis- 
taken for  the  house  fly  is  the  Anthomyidae,  but  none 
of  these  has  an  elbowed  vein. 

"In  the  foregoing  paragraph  I  stated  that  the  house 
fly  can  be  distinguished  from  nearly  all  of  the  other 
kinds  of  flies  that  resemble  it  by  the  two  characters 
mentioned.  We  have,  in  this  country,  a  species  agree- 
ing with  it  even  in  regard  to  the  two  characters  given. 
Indeed  the  resemblance  is  so  close  that  only  an  ex- 
amination under  a  lens  or  microscope  will  reveal  the 
principal  difference  existing  between  these  two  spe- 
cies. I  refer  to  Musca  autiujiualis  DeGeer.*  In  the 
male  of  this  form  the  eyes  are  in  contact  on  the  upper 
part  of  the  head,  whereas  in  the  male  of  the  house  fly 
the  eyes  are  widely  separated  and  the  black  stripe  be- 
tween them  is  of  nearly  the  same  width  throughout  its 
length.  In  the  female  of  autvmnalis  the  dark  stripe 
between  the  eyes  is  only  as  wide  as  the  added  breadth 
of  the  narrowest  part  of  the  two  gray  stripes  which 

*The  Musca  corvina  Fabricius,  1781. 


ZOOLOGICAL  POSITION  5 

border  it,  while  in  the  female  of  the  house  fly  this 
dark  stripe  almost  touches  the  eyes.  Autumnalis,  like 
its  near  relative,  is  almost  cosmopolitan,  but  appears 
to  have  been  rarely  met  with  in  this  country." 

Possibly  a  simpler  way  of  putting  it  would  be  as 
follows : 

Musca  domcstica  has  four  black  lines  on  the  back 
of  its  thorax.  All  Sarcophagidae  have  three  such  black 
lines.  Most  Tachinidee  have  four  such  black  lines, 
but  the  Tachinidse  have  the  bristle  of  the  antennae 
smooth,  whereas  in  Musca  domestica  this  bristle  is 
feathered.  From  all  Anthomyidae,  Musca  domestica 
is  at  once  separated  by  the  bent  vein  near  the  tip  of 
the  wing.  Moreover,  Musca  domestica  has  no  bristles 
on  the  abdomen  except  at  the  tip  which  separates  it 
from  all  others  except  some  Tachinids  and  many  An- 
thomyids,  but  from  these  it  is  separated  by  the  char- 
acters given  above. 

Musca  domestica  is  not  alone  in  its  genus.  There 
are  fifteen  species  of  the  genus  Musca  according  to 
Bezzi  and  Stein  in  their  Catalogue  of  the  Palearctic 
Diptera.  In  North  America  there  are  thirteen  species 
of  Musca,  according  to  Aldrich.  Of  none  of  these 
other  species  of  Musca  do  the  habits  appear  to  be 
known.  There  is,  however,  an  Indian  species,  Musca 
cntccniata,  which  breeds  in  the  same  fecal  masses  with 
the  typhoid  fly. 


6      THE  HOUSE  FLY— DISEASE  CARRIER 

LIFE  HISTORY 

A  long  experience  with  the  study  of  insects  has  in- 
dicated the  somewhat  remarkable  fact  that  it  is  about 
the  commonest  things  in  general  that  we  know  the 
least.  When  Mr.  C.  L.  Marlatt  and  the  writer  began 
in  1895  to  work  on  the  subject  of  household  insects, 
we  discovered  that  very  few  of  the  species  found  so 
abundantly  in  households  were  included  in  the  museum 
collections.  There  would  be  a  large  series  of  a  rare 
beetle  from  Brazil,  but  no  specimens  of  the  common 
house  cockroach,  for  example ;  and  when  we  began  to 
look  into  the  literature  of  their  life  histories  we  learned 
that  published  accounts  of  their  transformations  were 
even  more  scarce  than  the  specimens  in  the  collections. 
Doctor  Hewitt  (1910)  calls  attention  to  the  vision  of 
Sir  James  Crichton  Browne  of  the  aged  person  show- 
ing the  wondering  child  the  only  existing  specimen  of 
the  house  fly,  in  the  British  Museum.  This  was  in- 
tended as  a  prophecy,  but  it  would  not  be  surprising 
if  before  the  recent  house  fly  crusade  began  there 
really  was  only  one  specimen  of  the  house  fly  in  the 
British  Museum. 

With  this  condition  of  affairs  existing  in  general, 
it  is  perhaps  not  so  surprising  that  an  exhaustive  study 
of  the  conditions  which  produce  house  flies  in  numbers 
has  really  never  been  made.  The  life  history  of  the 
insect  was,  down  to  1873,  mentioned  in  only  a  few  old 
European  works  and  one  more  modern  one  (Taschen- 


LIFE  HISTORY  7 

berg).*  In  1873,  Dr.  A.  S.  Packard  (1874),  then  of 
Salem,  Mass.,  studied  the  transformations  of  the  in- 
sect and  gave  descriptions  of  all  the  stages,  showing 
that  the  growth  of  a  generation  from  the  egg  to  the 
adult  state  occupies  from  ten  to  fourteen  days.  In 
1895,  the  writer  traced  the  fly's  life  history,  discover- 
ing that  120  eggs  are  laid  by  a  single  female  at  a  time 
and  that  in  Washington  in  midsummer  a  generation  is 
produced  in  ten  days. 

Substances  in  Which  This  Fly  Passes  Its  Early  Life 

It  is  safe  to  say  that  the  typhoid  fly  will  breed  in 
almost  any  fermenting  organic  matter,  and  it  is  also 
probably  safe  to  say  that  if  given  its  preference  it  will 
lay  its  eggs  on  a  pile  of  horse  manure.  The  writer 
once  estimated  that  under  ordinary  city  and  town  con- 
ditions more  than  ninety  per  cent,  of  the  flies  present 
in  houses  have  come  from  horse  stables  or  their  vi- 
cinity, and  he  is  still  inclined  to  think  that  this  esti- 
mate is  probably  correct.  But  the  eggs  will  also  be 
laid  upon  the  excreta  of  almost  any  animal.  Cow 
manure  drying  rapidly  in  a  dry  season  and  forming  a 
hardened  caked  surface  is  not  a  favorable  nidus,  yet  this 
fly  is  reared  from  cow  manure  at  times.  Many  other 
species  of  flies  prefer  cow  manure,  and  a  long  list  of 

*The  best  of  these  old  papers  is  little  known.  It  was  published 
at  Nurenberg  in  1764,  and  is  entitled  "Geschichte  der  gemeinen 
Stubenfliege,  Herausgeben  von  J.  C.  Keller"  and  covers  thirty- 
four  pages  of  text  and  four  plates.  The  real  author  is  said  by 
Hagen  to  be  Freiherr  Friedrich  Wilhelm  von  Gleichen  (genannt 
Russworm). 


8      THE  HOUSE  FLY— DISEASE  CARRIER 

species  reared  from  this  substance  has  been  published 
by  the  writer  (1901). 

The  typhoid  fly  is,  possibly  next  to  horse  manure, 
attracted  to  human  excreta,  and  not  only  visits  it  wher- 
ever possible  for  food,  but  lays  its  eggs  upon  it  and 
lives  during  its  larval  life  within  it.  It  will  not  only 
do  this  in  the  latrines  of  army  camps,  in  the  open  box 
privies  of  rural  districts  and  small  villages,  but  also 
upon  chance  droppings  in  the  field  or  in  the  back  alley- 
ways of  cities,  as  has  been  repeatedly  shown  experi- 
mentally in  Washington. 

It  may  very  readily  happen  that  the  flies  of  any  given 
neighborhood  have  come  from  a  single  source,  and 
that  the  substances  in  which  they  breed  differ  accord- 
ing to  locality  and  according  to  the  supply  of  breed- 
ing substance.  Under  ordinary  city  conditions,  un- 
doubtedly the  most  frequent  nidus  is  in  the  horse 
manure  of  stables,  but  when  the  conditions  in  a  com- 
munity of  a  radically  different  nature  are  studied  the 
result  is  sometimes  surprising.  In  the  course  of  his 
investigations  of  conditions  in  small  towns  with  espe- 
cial reference  to  the  hookworm  disease,  Stiles  has  found 
that  in  cotton-mill  towns,  for  example,  the  privies  may 
be  a  much  more  important  breeding  place  of  flies  than 
the  manure  piles,  not  only  more  important  since  flies 
breeding  in  this  substance  are  more  likely  to  carry 
disease  germs,  but  also  numerically  more  important; 
for  you  may  have  250  uncared-for  privies  and  perhaps 
only  one  or  even  no  manure  pile.  And  there  are  com- 
munities also  where  horses  are  scarce  and  pigs  are 


LIFE  HISTORY  9 

numerous.  Stiles  has  seen  great  accumulations  of  pig 
manure  fairly  swarming  with  fly  larvse. 

With  regard  to  ordinary  kitchen  refuse,  such  as  is 
found  in  the  garbage  pail,  it  is  the  opinion  of  Prof. 
J.  S.  Hine,  of  the  Ohio  State  University,  who  has  paid 
much  attention  to  the  subject,  that,  while  house  flies 
visit  garbage  in  numbers,  they  appear  in  most  cases 
to  be  after  food  only,  as  only  a  few  specimens  of  this 
species  were  reared  from  such  material  during  the  sea- 
son when  he  was  at  work. 

With  fermenting  vegetable  refuse  from  the  kitchen, 
he  found  that  the  very  common  fly  which  bred  in  it 
was  not  the  typhoid  fly,  but  Muscina  stabulans,  the  so- 
called  stable  fly.  Hundreds  of  these  flies  were  reared 
and  their  larvae  were  exceedingly  abundant  in  all  of 
the  samples  of  garbage  examined.  Musca  domestica 
was  also  reared,  as  was  also  another  species  known  as 
Phormia  regina,  but  it  seems  from  these  observations, 
although  they  were  limited  to  a  single  locality  in  Cen- 
tral Ohio,  that  the  recently  acquired  general  opinion 
to  the  effect  that  the  typhoid  fly  breeds  abundantly  in 
vegetable  refuse  when  it  has  reached  the  proper  fer- 
menting stage  is  due  many  times  to  the  mistake  of 
considering  the  stable  fly  and  its  larvae  as  those  of  M. 
domestica.  And  this  is  an  important  point,  since  the 
stable  fly  is  rather  rarely  found  in  houses  and  on  food 
and  therefore  is  not  an  important  carrier  of  disease. 

The  substances  in  which  flies  will  breed  were  care- 
fully investigated  in  the  city  of  Liverpool  by  Mr.  Rob- 
ert Newstead,  lecturer  in  economic  entomology  and 


10    THE  HOUSE  FLY— DISEASE  CARRIER 

parasitology  in  the  School  of  Tropical  Medicine  of  the 
University  of  Liverpool  in  1907.  Mr.  Newstead  is  of 
the  opinion  that  the  chief  breeding  places  of  the  house 
fly  in  Liverpool  should  be  classified  under  the  follow- 
ing heads:  (i)  Middensteads  (places  where  dung  is 
stored)  containing  horse  manure  only;  (2)  Midden- 
steads  containing  spent  hops;  (3)  Ash  pits  containing 
fermenting  materials.  He  found,  as  has  been  the  ex- 
perience of  observers  in  this  country  and  India,  that 
the  dung  heaps  of  stables  containing  horse  manure 
only  were  the  chief  breeding  places.  Where  horse  and 
cow  manures  were  mixed  the  flies  bred  less  numer- 
ously, and  in  barnyards  where  fowls  were  kept  and  al- 
lowed freedom  comparatively  few  flies  were  found. 
Only  one  midden  containing  warm  spent  hops  was  in- 
spected, and  this  was  found  to  be  as  badly  infested  as 
any  of  the  stable  middens.  A  great  deal  of  time  was 
given  to  the  inspection  of  ash  pits,  and  it  was  found 
that  wherever  fermentation  had  taken  place  and  arti- 
ficial heat  had  been  thus  produced  such  places  were 
infested  with  house  fly  larvae  and  pupae,  often  to  the 
same  extent  as  in  stable  manure.  Such  ash  pits  as 
these  almost  invariably  contained  large  quantities  of 
old  bedding  or  straw  and  paper,  paper  mixed  with  hu- 
man excrement,  or  old  rags,  manure  from  rabbit 
hutches,  etc.,  or  a  mixture  of  all  of  these.  About 
twenty-five  per  cent,  of  the  ash  pits  examined  were 
thus  infested,  and  house  flies  were  found  breeding  in 
smaller  numbers  in  ash  pits  in  which  no  heat  had  been 
engendered  by  fermentation.  The  typhoid  fly  was  also 


LIFE  HISTORY  11 

found  breeding  by  Mr.  Newstead  in  certain  temporary 
breeding  places,  such  as  collections  of  fermenting  vege- 
table refuse,  accumulations  of  manure  at  the  wharves 
and  in  bedding  in  poultry  pens.  Mr.  F.  V.  Theobald 
states  that  swarms  of  flies  are  reported  to  breed  in  the 
huge  masses  of  dust-bin  refuse  in  certain  London  sub- 
urbs. It  does  not  appear  to  be  certain,  however,  that 
these  are  Musca  domestica. 

In  India,  according  to  the  observations  of  Surgeon 
Major  F.  Smith,  of  the  Royal  Army  Medical  Corps, 
horse  manure  is  the  most  abundant  breeding  place  for  the 
house  fly  around  military  stations.  He  also  reared  this 
fly  from  cow  dung  in  company  with  Musca  entaniata. 

DeGeer  states  that  the  larvae  of  this  species  live  in 
dung,  but  only  in  that  which  is  warm  and  moist,  or, 
stated  better,  which  is  in  a  condition  of  perfect  fermen- 
tation. The  importance  of  the  factor  of  fermentation 
has  already  been  referred  to  in  the  account  of  Mr. 
Newstead's  observations  and  is  insisted  upon  by  Dr. 
C.  Gordon  Hewitt  in  Part  II  of  his  important  paper 
on  the  Structure,  Development  and  Bionomics  of  the 
House  Fly.  He  points  out  that  Keller,  writing  of  this 
fly  in  1790,  reared  the  larvae  of  the  typhoid  fly  in  de- 
caying grain,  where  no  doubt  fermentation  was  taking 
place;  also  in  small  portions  of  meat,  slices  of  melon, 
and  in  old  broth.  Doctor  Hewitt  also  found  that  horse 
manure  is  preferred  to  all  other  substances  by  the  fe- 
male flies  for  egg-laying.  He  also  found  that  the  lar- 
vae will  feed  upon  paper  and  textile  fabrics,  such  as 
woolen  and  cotton  garments  and  sacking  which  were 


12    THE  HOUSE  FLY— DISEASE  CARRIER 

foul  with  excremental  products,  if  they  were  kept  moist 
and  at  a  suitable  temperature.  He  also  reared  adult 
flies  from  decaying  vegetables  thrown  away  as  kitchen 
refuse,  and  on  such  fruits  as  bananas,  apricots,  cherries, 
plums,  and  peaches,  which  were  mixed  when  in  a  rot- 
ting condition  with  earth  to  make  a  more  solid  mass. 
He  succeeded  in  rearing  them  in  bread  soaked  in  milk 
and  boiled  egg  and  kept  at  a  temperature  of  25°  C, 
but  he  was  unable  to  rear  them  to  maturity  in  cheese. 
The  preference  which  the  typhoid  fly  has  for  horse 
manure  as  a  breeding  nidus  has  been  clearly  shown 
by  a  multitude  of  observations.  One  of  the  early  ex- 
periences of  the  writer  consisted  in  an  effort  to  keep 
the  stables  of  the  U.  S.  Department  of  Agriculture  at 
Washington  in  a  strictly  sanitary  condition.  The  ma- 
nure was  swept  up  and  placed  each  day  in  a  screened 
closet.  As  a  result  there  was  a  notable  diminution  of 
flies  in  all  of  the  buildings  for  hundreds  of  yards 
around  for  several  weeks ;  whereas  up  to  the  time  when 
the  experiment  began  they  had  been  a  nuisance  through- 
out that  portion  of  the  city.  One  of  the  many  letters 
received  which  bear  upon  this  point  may  be  quoted : 

WASHINGTON,  D.  C,  February  10,  1908. 
"DR.  L.  O.  HOWARD, 

Department  of  Agriculture, 

Washington,  D.  C. 
"DEAR  DR.  HOWARD: 

"For  the  greater  part  of  the  last  two  years  I  have  oc- 
cupied a  room  on  the  third  floor  of  the  Faculty  Club  on 
the  Campus  of  the  University  of  California  at  Berkeley, 
Calif.  During  most  of  the  time  the  number  of  flies  in 


LIFE  HISTORY  13 

the  Club  House  has  been  notably  small,  considering  the 
fact  that  the  Club  maintains  a  dining-room  and  its  win- 
dows and  doors  are  not  screened.  A  year  ago  last  fall 
there  was  a  sudden  incursion  of  flies,  so  that  they  created 
much  annoyance  in  all  parts  of  the  Club  House ;  and  they 
were  specially  abundant  in  my  room.  I  protected  my 
windows  by  screens,  and  then  captured  the  flies  on  sticky 
fly  paper,  securing  in  that  way  more  than  2,000.  The 
nuisance  in  other  rooms  continued  several  weeks  longer, 
and  then  gradually  abated.  There  was  no  recurrence  at 
the  corresponding  season  last  fall. 

"Recalling  some  statements  of  yours  with  reference  to 
the  life  history  of  the  house  fly,  I  noted  that  the  epidemic 
was  coincident  with  the  grading  of  the  University  ath- 
letic field,  about  200  yards  from  the  Faculty  Club,  and 
that  in  that  grading  many  horses  were  employed,  probably 
as  many  as  fifty.  So  far  as  I  am  aware  there  are  no 
horses  stabled  on  the  University  campus,  and  I  do  not 
recall  having  seen  any  horse  stables  at  a  less  distance  than 
two  blocks,  or,  say,  three  times  the  distance  of  the  athletic 
field.  These  various  relations  of  time  and  space  serve  to 
connect  the  local  fly  epidemic  in  a  fairly  definite  way  with 
the  temporary  proximity  of  a  large  number  of  horses. 
"Yours  very  truly, 

"G.  K.  GILBERT." 

In  an  article  entitled  "Experiments  on  Transmission 
of  Bacteria  by  Flies  with  Especial  Relation  to  an  Epi- 
demic of  Bacillary  Dysentery  at  the  Worcester  State 
Hospital,"  Dr.  Samuel  T.  Orton  (1910),  after  describ- 
ing a  series  of  very  interesting  experiments  indicating 
the  spread  of  a  species  of  bacillus  throughout  the  in- 
stitution by  the  agency  of  flies,  describes  a  search  made 
to  discover  the  breeding  places  of  the  unusual  number 
of  flies  infesting  the  hospital.  Searching  first  for  horse 


14    THE  HOUSE  FLY— DISEASE  CARRIER 

manure,  he  found  that  there  were  only  two  such  ac- 
cumulations on  the  hospital  grounds.  The  one  at  the 
stable  was  in  a  large  masonry  pit  drained  below  and 
covered  so  that  while  not  fly-proof  it  was  dark  and  dry. 
No  larvae  or  puparia  were  found  in  the  pit.  The  ma- 
nure was  molding  and  heating  rapidly.  Two  other 
piles  where  the  manure  was  kept  dry  and  in  the  dark 
showed  the  same  condition  of  rapid  heating  and  mold- 
ing and  no  larvae  were  found.  At  the  farm  barn  the 
manure  was  dropped  through  four  traps  where  a  pile 
accumulated,  and  was  then  taken  to  the  part  of  the 
barn  where  the  cow  manure  is  collected  and  the  two 
were  mixed  together.  Here  a  considerable  number 
of  larvae  and  puparia  were  found,  but  not  in  sufficiently 
great  numbers  to  account  for  the  swarms  around  the 
buildings.  They  were  more  abundant  in  the  part  of 
the  pile  which  consisted  of  pure  horse  manure  and 
grew  noticeably  less  until  the  cow  manure  was  reached, 
when  they  were  very  few.  Examination  of  the  pig 
pen  showed  piles  of  pig  manure  mixed  with  the  straw 
bedding  exposed  to  air  and  rain.  This  was  badly  in- 
fested ;  one  ounce  of  material  taken  from  a  point  a  few 
inches  below  the  surface  displayed  868  puparia.  An- 
other prolific  source  was  found  in  piles  of  spent  hops 
and  barley  malt — brewery  waste  which  had  been  hauled 
in  as  a  fertilizer.  The  hops  showed  a  tendency  to  mold 
rapidly,  and  the  flies  did  not  breed  in  it  as  abundantly 
as  in  the  looser  barley  malt.  In  parts  of  the  malt  where 
there  was  plenty  of  moisture  the  maggots  were  ex- 
tremely numerous;  one  ounce  contained  1,018  mag- 


LIFE  HISTORY  15 

gots.  There  had  been  considerable  rain  and  the  piles 
were  damp  throughout.  At  one  place  there  was  a  layer 
of  six  or  eight  inches  of  soggy  barley  over  the  ground, 
which  was  simply  crawling  with  larvae.  After  six  days 
of  continued  dry  weather,  however,  they  had  practically 
all  disappeared. 

An  interesting  experiment  was  made.  One  pound 
of  material  from  each  of  the  breeding  places  was  taken 
to  the  laboratory  and  kept  in  screen-covered  glass  jars 
for  ten  days,  with  the  following  result: 

Stable  manure o  adult  flies  issued 

Farm  barn,  horse  end ....  77 

Farm  barn,  mixed 19 

Farm  barn,  cow  end I 


Piggery  manure  pile 361 

Spent  hops 129 

Barley  malt 539 


fly 
flies 


These  results  as  recorded  are  very  interesting  and 
are  probably  in  the  main  correct,  although  Doctor  Or- 
ton  states  that  the  identification  of  species  was  by  no 
means  thorough  and  the  determination  of  the  house 
fly  was  made  simply  by  observation  of  its  size  and  gen- 
eral appearance  and  the  characters  of  the  mouth  parts. 
It  is  possible  that  the  stable  fly  (Muscina  stabulans) 
may  have  formed  a  portion  at  least  of  the  flies  bred 
from  the  spent  hops  and  the  barley  malt. 

There  is  a  statement  in  Taschenberg's  Praktische 
Insektenkunde  to  the  effect  that  the  female  house  fly 
lays  its  eggs  not  only  upon  spoiled  and  moist  food- 
stuffs, decaying  meat,  meat  broth,  cut  melons,  dead 
animals,  manure  pits,  manure  heaps,  but  even  in  cus- 


16    THE  HOUSE  FLY— DISEASE  CARRIER 

pidors  and  open  snuff-boxes.  The  entomological  world 
has  accepted  the  statement,  with,  however,  some  doubt 
as  to  the  snuff-boxes.  Prof.  S.  A.  Forbes,  however, 
informs  the  writer  that  August  22,  1889,  ne  received 
from  an  old  friend,  T.  A.  E.  Holcomb,  then  a  druggist 
at  Kensington,  111.,  a  box  of  snuff  containing  dipterous 
larvae.  From  these  dipterous  larvae  Professor  Forbes 
bred  the  true  house  fly.  His  recollection  of  the  matter 
is  very  clear,  and  he  has  now  in  his  collection  a  very 
under-sized  specimen  labeled  Musca  domcstica  and 
bearing  an  old  pencil  label  in  his  handwriting,  "Snuff, 
August  26th." 

He  afterwards  called  upon  Mr.  Holcomb  in  his  drug 
store  and  learned  that  among  his  constant  customers 
were  some  old  foreigners  who  came  so  frequently  t<> 
have  their  snuff-boxes  filled  that  for  convenience  in 
serving  them  he  was  accustomed  to  keep  an  open  box 
of  snuff  upon  one  of  his  show-cases,  and  from  this  box 
the  specimens  came. 

A  very  important  series  of  observations  was  carried 
on  under  the  direction  of  Professor  Forbes  in  the  sum- 
mers of  1908-1909  by  his  assistants,  Mr.  A.  A.  Girault, 
at  Urbana,  and  Mr.  J.  J.  Davis,  in  Chicago,  for  the  pur- 
pose of  ascertaining  exactly  what  other  substances 
aside  from  horse  manure  will  serve  as  breeding  places 
for  house  flies.  The  results  of  these  observations,  not 
previously  published,  have  been  placed  at  the  writer's 
disposal  by  Professor  Forbes.  They  constitute  a  very 
valuable  addition  to  our  knowledge  on  this  subject.  It 
was  a  surprise  to  find  that  nearly  a  thousand  flies  had 


LIFE  HISTORY  17 

been  reared  from  cow  dung.  This  dung  was  in  a  stable, 
and  it  is  to  be  presumed  that  the  conditions  were  such 
that  the  dung  did  not  dry  readily  and  that  there  was 
no  preferred  food  in  the  immediate  vicinity.  Precon- 
ceived notions  are  also  somewhat  upset  by  the  rearing 
of  267  flies  from  carrion  found  in  the  street.  The  list 
as  a  whole  is  of  the  greatest  practical  interest  and  is 

asfollows:  Number  house 

Date  Media  flies  bred 

Sept.  1-3 Rotten  water-melon  and  muskmelon  14^ 

Aug.  18  and 

Sept.  8-1 1 Rotten  carrots  and  cucumbers 23  -" 

Sept.  7 Rotten  cabbage  stump i  - 

Sept.  7 Banana  peelings i^~ 

Aug.  30 Rotten  potato  peelings 12  "" 

Sept.  25 Cooked  peas  i  - 

Oct.   i    Ashes  mixed  with  vegetable  wastes.  i 

Sept.  7-14 Rotten  bread  or  cake 8 "" 

Aug.  22 Kitchen  slops  and  offal 193  ^ 

Sept.  10-26 Mixed  sawdust  and  rotting  vege- 
tables    41  / 

Aug.  3O-Sept.  4. .  Old  garbage,  city  dump 15 

Aug.  14  and  18..  Rotten  meat,  slaughter  houses . .  40 

Aug.  3o-Sept.  ii. Carrion  in  street 267 

Sept.  7 Seepage  from  garbage  pile i 

Aug.  17-20 Hogs'  hair,  slaughter  house  waste..  9 

Aug.  23-28 Sawdust   sweepings,    Stock   Yards 

slaughter  house   no 

Aug.  23 Sawdust  sweepings,  meat  market...  4 

Aug.  16-28 Animal  refuse,  Stock  Yards 39 

Aug.  14 Contents   of  paunches   of   slaugh- 
tered cattle   168 

Sept.  2- 1 1 Rotten  chicken  feathers 258 

Aug.  16 Chicken  manure,  stock-car  dump. ...  3 

Aug.  3i-Sept.  7.  .Cow-dung,  stable,  Urbana 997 

Sept.  7-10 Cow-dung,  outdoor  yard   22 

Sept.  6 Cow-dung,  pasture   i 

Aug.  24-Sept.  16.  Human  excrement   196 


18    THE  HOUSE  FLY— DISEASE  CARRIER 

The  Egg 

The  eggs  are  minute  and  glistening  white,  and  they 
are  all  long  ovoid  in  shape.  In  length  they  vary  from 
one-sixth  of  an  inch  to  a  little  longer.  They  are  laid 
in  clusters  of  small  size  and  irregular  shape,  either  on 
their  ends  or  on  their  sides.  Seen  under  a  high  power  of 
the  microscope,  the  polished  surface  appears  to  be  cov- 
ered with  minute  hexagonal  markings  such  as  is  seen 
in  what  the  histologist  calls  pavement  epithelium.  Each 
female  fly  lays  on  the  average  120  eggs,  or  perhaps 
more,  at  a  time  and  may  lay  several  times.  Forbes' s 
assistants  in  Illinois  found  that  eggs  from  a  single  fly 
vary  from  120  to  150  in  each  deposit  and  that  as  many 
as  four  deposits  may  be  made,  or  say,  600  eggs  by  a 
single  fly  (in  lit.).  One  hundred  and  twenty  was  the 
number  observed  by  the  writer  to  be  the  average  num- 
ber, but  Doctor  Hewitt  has  counted  as  many  as  150. 

The  duration  of  the  egg  stage,  as  observed  in  Wash- 
ington, was  usually  eight  hours;  that  is  to  say,  eight 
hours  after  it  was  laid  the  egg  hatched.  These  ob- 
servations were  made  in  midsummer  and  have  not  been 
repeated  at  other  times  of  the  year.  Mr.  Newstead  in 
Liverpool  found  that  the  eggs  hatched  in  periods  vary- 
ing from  eight  hours  to  three  or  four  days,  the  average 
time  being  about  twelve  hours.  But  he  noted  that  when 
laid  in  fermenting  materials  the  incubation  period  was 
reduced  to  a  minimum  of  eight  to  twelve  hours.  In 
a  temperature  of  from  75°  F.  to  80°  F.  they  hatched 
in  from  eight  to  twelve  hours;  in  a  temperature  of  60° 


Fig.  i. — Eggs,  approximately  natural  size;  photographed  on  surface 
manure  pile.     (From  Newstead.) 


ERRATUM 
p.  18,  line  3,  one-sixth  should  be  one-twentieth 


the  microscope,  the  polished  surface  appears  to  be  cov- 
ered with  minute  hexagonal  markings  such  as  is  seen 
in  what  the  histologist  calls  pavement  epithelium.  Each 
female  fly  lays  on  the  average  120  eggs,  or  perhaps 
more,  at  a  time  and  may  lay  several  times.  Forbes' s 
assistants  in  Illinois  found  that  eggs  from  a  single  fly 
vary  from  120  to  150  in  each  deposit  and  that  as  many 
as  four  deposits  may  be  made,  or  say,  600  eggs  by  a 
single  fly  (in  lit.).  One  hundred  and  twenty  was  the 
number  observed  by  the  writer  to  be  the  average  num- 
ber, but  Doctor  Hewitt  has  counted  as  many  as  150. 
The  duration  of  the  egg  stage,  as  observed  in  Wash- 
ington, was  usually  eight  hours;  that  is  to  say,  eight 
hours  after  it  was  laid  the  egg  hatched.  These  ob- 
servations were  made  in  midsummer  and  have  not  been 
repeated  at  other  times  of  the  year.  Mr.  Newstead  in 
Liverpool  found  that  the  eggs  hatched  in  periods  vary- 
ing from  eight  hours  to  three  or  four  days,  the  average 
time  being  about  twelve  hours.  But  he  noted  that  when 
laid  in  fermenting  materials  the  incubation  period  was 
reduced  to  a  minimum  of  eight  to  twelve  hours.  In 
a  temperature  of  from  75°  F.  to  80°  F.  they  hatched 
in  from  eight  to  twelve  hours;  in  a  temperature  of  60° 


Fig.  i. — Eggs,  approximately  natural  size;  photographed  on  surface  of 
manure  pile.     (From  Newstead.) 


Fig.  2. — Eggs,  approximately  natural  size.     (From  Newstead.) 


LIFE  HISTORY  19 

R,  in  twelve  hours,  but  at  45°  F.  they  did  not  hatch 
until  the  third  day,  and  then  only  when  placed  in  a 
warmer  temperature  for  the  purpose  of  studying  them 
under  the  microscope. 

Doctor  Hewitt  has  carefully  observed  the  hatching 
of  the  eggs,  and  this  is  a  process  which  has  now  be- 
come familiar  to  many  Americans  through  the  excel- 
lent moving-picture  exhibitions  given  under  the  auspices 
of  the  American  Civic  Association  from  films  prepared 
in  England  at  the  expense  of  Mr.  Daniel  Hatch,  Jr., 

m 


Fig.  5.— Egg  of  house  fly;  greatly  enlarged.     (Original.) 

Chairman  of  the  Fly-fighting  Committee  of  the  Asso- 
ciation.    Doctor  Hewitt's  description  follows : 

"A  minute  split  appeared  at  the  anterior  end  of  the 
dorsal  side  to  the  outside  of  one  of  the  ribs  [refer- 
ring to  two  distinct  curved  rib-like  thickenings  along 
the  dorsal  side  of  the  egg]  ;  this  split  was  continued 
posteriorly  and  the  larva  crawled  out,  the  walls  of  the 
chorion  [the  eggshell]  collapsing  after  its  emergence. 

The  Larva 

We  have  just  described  how  the  egg  hatches.  The 
young  larva  as  it  issues  from  the  egg  is  a  slender 


20    THE  HOUSE  FLY— DISEASE  CARRIER 

creature  tapering  from  the  blunt,  round,  hinder  end 
to  the  pointed  head  end.  It  is  glistening  white  in 
color  and  only  about  two  mm.  in  length.  It  is  ex- 
tremely active  and  burrows  at  once  into  the  substance 
upon  which  the  egg  from  which  it  hatched  had  been 
laid,  rapidly  disappearing  from  sight.  In  the  course 
of  its  growth  it  casts  its  skin  twice,  and  therefore 
passes  through  three  distinct  stages  of  growth.  In  the 
first  one  the  anal  spiracles,  or  breathing  holes,  on  the 
last  segment,  are  contained  in  a  heart-shaped  aperture. 
After  the  first  molt  these  spiracles  issue  in  two  slits,  and 
after  the  second  molt  there  are  three  winding  slits. 

In  the  third  and  last  stage  the  larva  is  still  white, 
sometimes  appearing  yellowish.  It  is  slender  and  taper- 
ing in  front,  large  and  truncate  behind.  The  head  has 
a  tiny  papilla  on  each  side.  There  is  one  great  hook 
above  the  mouth  orifice.  On  each  side  of  the  pro- 
thorax  there  are  spiracles  which  show  six  or  seven 
lobes.  On  the  ventral  base  of  the  sixth  and  following 
segments  there  is  a  transverse  fusiform,  swollen  area 
provided  with  minute  teeth.  The  anal  area  is  only 
slightly  prominent,  and  shows  two  processes  close  to- 
gether. The  anal  spiracles  are  prominent,  less  than 
their  diameter  apart,  and  each  with  three  sinuous  slits 
and  a  button  at  the  base.  In  some  cases  two  of  the 
winding  slits  are  apparently  connected  together.  With- 
in the  head,  or  rather  the  anterior  part  of  the  body, 
is  a  chitinous  framework  consisting  of  several  articu- 
lated parts  called  the  cephalopharyngeal  skeleton,  which 
is  indicated  in  figure  7. 


Fig.  3. — Eggs,  greatly  enlarged.     (From  Newstead.) 


Fig.  4. — Eggs,  greatly  enlarged — another  view.     (From  Newstead.) 


LIFE  HISTORY  21 

The  rate  of  growth  of  the  house  fly  larva  varies  ac- 
cording to  temperature  in  much  the  same  way  as  does 
the  period  of  duration  of  the  egg  stage.  In  the  writ- 
er's original  observations  in  midsummer  in  Washing- 
ton he  found  that  the  time  from  the  hatching  to  the 
first  molt  was  twenty-four  hours ;  from  the  first  molt  to 
the  second  molt  twenty-four  hours;  from  the  second 
molt  to  transformation  to  pupa  seventy-two  hours ;  mak- 
ing the  duration  of  larval  life  five  days.  The  larvae  are 
very  active  and  migrate  from  place  to  place  in  a  ma- 
nure pile  with  facility.  Mr.  Newstead  in  Liverpool  ob- 
served that  they  mature  in  the  shortest  period  in  fer- 
menting materials  in  a  temperature  of  between  90° 
and  98°  F.,  but  that  they  usually  leave  the  hotter  por- 
tions of  the  stable  manure  when  it  reaches  a  temper- 
ature of  from  100°  to  110°  F.  At  54°  F.  the  larval 
stage  was  considerably  prolonged,  and  larvae  kept  at 
that  temperature  had  not  matured  at  the  end  of  eight 
weeks. 

Doctor  Hewitt  at  Manchester,  England,  showed  that 
larvae  of  the  first  stage  might  molt  as  early  as  twenty 
hours  after  hatching,  but  that  from  twenty-four  to 
thirty-six  hours  usually  elapsed  before  ,the  first  molt. 
Under  favorable  conditions  of  temperature  larvae  in 
this  stage  remained  three  days  without  molting.  In 
molting  he  noted  that  the  skin  was  shed  from  the  head 
and  posteriorly,  and  that  not  only  the  skin  was  shed, 
but  also  the  cephalopharyngeal  sclerites,  as  well  as  the 
chitinous  lining  of  the  fore  portion  of  the  alimentary 
tract.  He  observed  that  the  second  stage  of  the  larvae 


22    THE  HOUSE  FLY— DISEASE  CARRIER 

might  last  only  twenty-four  hours,  but  at  a  lower  tem- 
perature or  with  a  deficiency  of  moisture  the  period 
was  prolonged  and  might  take  several  days.  The  third 
stage  occupied  as  a  rule  between  three  and  four  days. 

At  all  times  the  larvae  are  very  active.  When  their 
breeding  place  is  disturbed  they  wriggle  actively  about 
in  the  endeavor  to  conceal  themselves,  and  so  rapidly 
do  they  accomplish  this  purpose  that  it  is  difficult  to 
take  a  satisfactory  moving  picture  of  them,  or  indeed 
a  photograph  of  any  kind.  When  full-grown  and 
ready  to  transform,  the  yellowish  color  becomes  more 
pronounced,  owing  to  the  proliferation  of  fat  cells  in 
great  numbers  in  anticipation  of  the  resting,  non-feed- 
ing pupal  condition.  The  transformation  to  pupa  may 
take  place  almost  anywhere,  but  as  a  rule  there  is  an 
effort  on  the  part  of  the  larvae  to  descend  deeper  into 
the  manure  pile  or  other  substance  in  which  they  may 
be  living,  and  sometimes,  when  the  substance  upon 
which  they  have  fed  is  moist  and  the  earth  below  it  is 
also  moist  and  easy  of  entrance,  they  may  descend  two 
or  three  inches  below  the  surface  of  the  ground. 

The  only  good  word  that  can  be  said  for  this  fly  is 
the  fact  that  its  larvae  destroy  enormous  quantities  of 
excrementitious  and  waste  material,  greatly  assisting 
the  bacteria  of  putrefaction.  E.  Guyenot  (1907) 
shows,  first,  that  the  liquefaction  of  albuminoid  sub- 
stances is  the  result  of  a  true  process  of  digestion  un- 
der the  influence  of  certain  germs  of  putrefaction; 
second,  that  fly  larvae,  absorbing  exclusively  liquid 
substances,  easily  assimilable,  have  the  digestive  tract 


Fig.  6. — Egg  hatching;  greatly  enlarged.     (Original.) 


c 


Fig.  7. — Full  grown  larva  of  house  fly ;  greatly  enlarged  :  a,  anal  spiracle ; 

b,  side  view  of  larva ;  c,  cephalo-pharyngeal  skeleton ;  d,  same ; 

e,  anal  spiracle  still  more  enlarged.     (Original.) 


LIFE  HISTORY  23 

reduced  to  the  minimum  and  do  not  produce  soluble 
ferments  in  appreciable  quantity;  third,  that  the  larvae 
accelerate  putrefaction  of  bodies  by  assisting  in  the 
increase  of  microbes;  fourth,  that  the  larvae  nourish 
themselves  at  the  expense  of  the  products  of  germ 
chemistry — the  germs  can  develop  rapidly  and  spread 
in  all  directions  only  by  the  assistance  of  the  larvae; 
there  exists  between  these  two  agents  of  putrefaction 
a  true  symbiosis.  These  conclusions,  although  reached 
by  a  study  of  two  species  of  the  genus  Lucilia,  are  un- 
doubtedly applicable  to  the  larvae  of  other  flies  feeding 
in  animal  material. 

The  Pupa  and  Puparium 

Before  beginning  its  transformation  to  the  pupa, 
the  full-grown  larva  empties  its  alimentary  canal,  con- 
tracts from  its  own  skin,  the  skin  itself  forming  a 
nearly  cylindrical  pupal  case,  the  posterior  portion  be- 
ing slightly  larger  in  diameter  than  the  anterior  and 
both  ends  being  equally  rounded.  It  is  then  about  six 
mm.  in  length  and  of  the  shape  shown  at  figure  n. 
At  first  this  pupal  skin  remains  pale  yellowish,  but 
rapidly  changes  to  red  and  finally  to  a  dark  chestnut 
color.  The  insect  inside  loses  its  tracheal  system,  which 
is  withdrawn  by  the  surrounding  skin  and  eventually 
remains  inside  of  the  skin  or  pupa  shell  but  outside  of 
the  insect  itself.  The  insect  rapidly  assumes  a  true  pupal 
shape,  and  at  the  end  of  thirty  hours,  according  to 
Doctor  Hewitt,  most  of  the  parts  of  the  future  fly  can 
be  distinguished,  although  they  are  sheathed  in  a  pro- 


24    THE  HOUSE  FLY— DISEASE  CARRIER 

tecting  nymphal  membrane.  A  fully  formed  pupa 
taken  from  the  pupal  sheath,  or  puparium  as  it  is  called, 
is  shown  in  figure  n. 

In  this  stage  in  Washington  in  midsummer  the 
writer  has  shown  the  normal  duration  to  be  about  five 
days.  Mr.  Newstead  gives  the  period  as  from  -five  to 


Fig.  ii. — House  fly  puparium  (at  left)  and  pupa  (at  right)  ; 
greatly  enlarged.     (Original.) 

seven  days  in  cases  where  there  is  heat  produced  by 
fermentation,  but  where  there  is  no  such  heat  the  stage 
may  last  from  fourteen  to  twenty-eight  days,  or  even 
considerably  longer.  Doctor  Hewitt  states  that  with 
a  constant  temperature  the  adult  flies  may  emerge  be- 
tween the  third  and  fourth  day  after  pupation,  but  that 
the  period  is  more  usually  four  or  five  days,  since  the 
larvae  when  ready  to  pupate  as  a  rule  leave  the  hotter 


Fig.  8. — Larvae  in  horse  manure.     (From  Newstead.) 


Fig.  9. — Larvae  and  puparia.     (From  Newstead.) 


LIFE  HISTORY  25 

portions  of  the  substance  in  which  they  have  been  feed- 
ing and  transform  in  the  cooler  portions.  He  sug- 
gests the  idea  that  this  migration  outward  may  be  a 
provision  for  the  more  easy  emergence  of  the  fly  when 
the  time  should  come.  In  some  cases  he  found  that  the 
pupal  stage  lasted  through  several  weeks,  but  he  was 
never  successful  in  keeping  pupae  through  the  winter. 
Mr.  Newstead  found  that  in  stable  middens  the  puparia 
occur  chiefly  at  the  sides  or  at  the  top  of  the  wall  or 
framework  of  the  receptacle  where  the  temperature  is 
lowest.  He  found  them  in  such  situations  often  packed 
together  in  large  masses  numbering  many  hundreds. 
In  ash  pits  he  found  the  same  conditions. 

Where  the  manure  is  in  small  piles,  or  is  partly  spread 
out,  the  full-grown  larvae  almost  ready  for  transforma- 
tion are  apt  to  migrate  into  the  loose  ground  under  the 
pile  or  from  the  edges  of  the  pile  outwards,  to  trans- 
form under  nearby  rubbish.  This  habit  may  have  a 
very  important  practical  value,  since  municipal  regu- 
lations of  individual  stable  practice  in  regard  to  the 
removal  of  manure  should  take  into  consideration  that 
such  removal  at  intervals  longer  than  those  required 
for  the  larva  to  reach  full  growth  may  result  in  the 
leaving  of  many  puparia,  except  of  course  in  cases 
where  especial  receptacles  for  manure  are  in  use. 

Emergence  of  the  Adult 

This  has  been  well  described  by  Doctor  Hewitt  as 
follows : 

"When  about  to  emerge,  the  fly  pushes  off  the  an- 


26    THE  HOUSE  FLY— DISEASE  CARRIER 

terior  end  of  the  pupal  case  in  dorsal  and  ventral  por- 
tions by  means  of  the  inflated  frontal  sac,  which  may 
be  seen  extruded  in  front  of  the  head  above  the  bases 
of  the  antennae.  The  splitting  of  the  anterior  end  of 
the  pupal  case  is  quite  regular,  a  circular  split  is  formed 
in  the  sixth  segment  and  two  lateral  splits  are  formed 
in  a  line  below  the  remains  of  the  anterior  spiracular 
processes  of  the  larva.  The  fly  levers  itself  up  out  of 
the  barrel-like  pupa  [puparium]  and  leaves  the  nymphal 
sheath.  With  the  help  of  the  frontal  sac,  which  it  al- 
ternately inflates  and  deflates,  it  makes  its  way  to  the 
exterior  of  the  heap  and  crawls  about  while  its  wings 
unfold  and  attain  their  ultimate  texture,  the  chitinous 
exoskeleton  hardening  at  the  same  time;  when  these 
processes  are  complete  the  perfect  insect  sets  out  on  its 


career." 


The  frontal  sac  just  mentioned  is  the  distended  mem- 
branous portion  of  the  front  of  the  head.  This  is  con- 
stantly distending  as  the  fly  walks  rapidly  about  after 
issuing.  When  it  is  contracted  at  this  early  time,  it 
forms  a  dull  area,  soft  and  fleshy-looking,  and  free 
from  hairs.  The  fly  possesses  the  power  of  distending 
it  into  a  bladder-like  expansion,  trapezoidal  in  outline 
and  almost  as  big  as  the  rest  of  the  head,  pushing  the 
antennae  down  out  of  sight.  This  membrane  is  evi- 
dently distended  with  air,  and,  as  pointed  out  by  Pack- 
ard, its  connection  with  the  tracheae  and  the  mechanism 
of  its  movements  would  form  a  very  interesting  sub- 
ject of  inquiry.  Lowne,  in  his  Anatomy  of  the  Blow- 
fly, has  described  a  similar  structure  with  that  insect, 


Fig.  10. — Puparia  on  a  bit  of  old  rotting  cloth  from  an  ash  barrel. 
(From  Newstead.) 


LIFE  HISTORY  27 

and  he  is  obviously  correct  in  supposing  it  to  be  a  pro- 
vision for  the  pushing  away  of  the  end  of  the  puparium 
when  the  pupa  emerges  from  its  case.  This  frontal 
sac  has  been  noticed  by  many  observers,  and  was  well 
described  as  long  ago  as  1764  by  Count  von  Gleichen. 

Structure  of  the  Adult 

In  the  section  on  zoological  position,  a  description 
has  been  given  of  the  characters  which  separate  the 
adult  typhoid  fly  or  house  fly  from  other  allied  or  sim- 
ilar flies.  The  excellent  illustrations  given  here  (fig- 
ures 12  and  13)  show  in  more  or  less  detail  its  exact 
structure.  'Especial  attention  should  be  called,  how- 
ever, to  the  character  of  the  mouth  parts  and  of  the 
feet.  The  whole  insect  is  more  or  less  bristly  and  well 
capable  of  carrying  micro-organisms  from  putrescent 
or  semi-liquid  substances,  but  the  mouth  parts  and  the 
feet  are  especially  adapted  to  this  purpose.  In  addition 
to  two  claws,  each  of  the  six  feet  is  supplied  with  two 
sticky  pads  of  a  light  color.  These  are  called  pulvilli. 
On  the  walking  surface  these  pads  are  closely  covered 
with  hairs  which  secrete  a  sticky  fluid,  and  it  is  by 
their  help  that  flies  are  able  to  walk  in  any  position 
upon  highly  polished  surfaces. 

The  mouth  parts  are  very  complicated,  but  form  in 
the  main  a  proboscis  which  is  not  fitted  for  piercing 
but  for  sucking  and  is  illustrated  so  well  in  figure  15 
that  detailed  description  will  be  unnecessary.  This 
organ  can  be  retracted  and  expanded  to  a  certain  extent. 
It  is  somewhat  complicated  in  structure  and  consists 


28    THE  HOUSE  FLY— DISEASE  CARRIER 

of  an  upper  and  a  lower  portion,  the  upper  portion 
bearing  two  curved  bristly  lobes.  The  lower  portion 
or  true  haustellum  expands  at  the  tip  into  two  lobes 
which  are  called  the  oral  lobes.  On  their  under  sur- 
face they  have  transverse  chitinous  bars  which  are 
called  false  tracheae  (pseudotracheae).  The  presence 
of  these  hard  ridges  under  the  oral  lobes  fit  it  to  a 
certain  extent  for  rasping  solid  food.  The  orifice  to 
the  haustellum  occurs  between  the  lobes. 

In  feeding  upon  fluid  or  semi-fluid  substances,  the 
oral  lobes  are  simply  applied  to  the  surface  and  the 
fluid  is  sucked  up.  When,  however,  they  feed  upon 
soluble  solids  the  process  is  somewhat  different.  Doc- 
tor Graham-Smith  has  carefully  watched  them  feeding 
upon  crystals  of  brown  sugar,  and  has  done  this 
through  the  Zeiss  binocular  microscope.  He  states  that 
the  oral  lobes  of  the  proboscis  are  very  widely  opened 
and  closely  applied  to  the  sugar.  Fluid  (saliva)  seems 
to  be  first  deposited  on  the  sugar  and  then  strong  suck- 
ing movements  are  made.  Doctor  Graham-Smith 
watched  a  fly  sucking  an  apparently  quite  dry  layer 
of  sputum.  It  put  out  large  quantities  of  saliva  from 
its  proboscis  and  seemed  to  suck  the  fluid  in  and  out 
until  a  fairly  large  area  of  the  dry  layer  of  sputum 
was  quite  moist;  then  as  much  as  possible  was  sucked 
up  and  the  fly  moved  away  to  another  spot.  The  same 
observer  noticed  that  flies  which  had  the  opportunity 
of  feeding  either  on  fluid  or  partly  dried  milk  often 
chose  the  drier  portions,  and  states  that  under  natural 
conditions  they  can  often  be  seen  sucking  the  dried 


LIFE  HISTORY  29 

remains  near  the  top  of  a  milk  jug.  They  constantly 
apply  their  mouth  parts  to  the  surface  over  which  they 
are  walking,  attempting  to  suck  up  some  nutrition, 
and  under  certain  conditions  the  imprints  of  their  oral 
lobes  can  afterwards  be  made  out  under  the  lens. 

In  order  to  understand  the  digestive  processes  of  a 
fly  and  to  comprehend  fully  just  what  a  disease  germ 


Fig.  16. — A  diagrammatic  figure  of  tjie  alimentary  canal  of  the 

house  fly ;  greatly  enlarged.    Ph.,  Pharynx ;  Oes.,  Esophagus ; 

P.  Ven.,  Proventriculus;  Ven.,  Stomach;  F.  Int.,  Fore 

intestine;  H.  Int.,  Hind  Intestine;  Cr.,  Crop; 

Rect.,  Rectum. 

passes  through  after  it  is  sucked  up  by  one  of  these 
creatures,  it  is  necessary  to  know  something  of  the 
structure  of  the  alimentary  canal.  This  is  simpler  with 
the  house  fly  than  with  many  other  flies,  more  so  in 
fact  than  that  of  the  blow  fly,  whose  anatomy  was  so 
carefully  worked  out  by  the  famous  English  micro- 
scopist,  Lowne.  It  consists  of  a  pharynx,  a  rather 
narrow  esophagus,  a  proventriculus  or  chyle  stomach, 
a  crop,  a  ventriculus  or  true  stomach,  a  fore  and  a  hind 


30    THE  HOUSE  FLY— DISEASE  CARRIER 

intestine.  The  proventriculus  is  a  nodular  structure 
with  muscular  walls  and  probably  acts  also  as  a  pump- 
ing stomach.  The  food,  passing  through  the  esophagus 
into  the  proventriculus,  immediately  goes  by  an  almost 
continuous  route  into  the  crop.  The  tube  leading  into 
the  crop  leads  out  from  the  proventriculus  on  the  under 
side  backwards  and  ends  in  the  crop  itself,  which  is  a 
double  organ  situated  in  the  lower  part  of  the  abdomen 
of  the  fly.  This  crop  is  really  a  temporary  storehouse 
for  the  fly's  food,  and  in  this  storehouse  it  remains 
practically  unchanged,  as  has  been  proved  by  exact 
experimentation.  Returning  from  the  crop,  possibly 
pumped  back  by  the  muscular  walls  of  the  proventricu- 
lus, it  recedes  again  into  the  true  stomach  or  ventricu- 
lus,  which  is  a  somewhat  expanded  tubular  organ  run- 
ning fore  and  aft  and  situated  above  the  tube  leading 
to  the  crop.  The  stomach  proper  extends  back  through 
the  thorax  under  the  big  muscles  of  the  back  and  into 
the  abdomen,  where  it  ends  just  over  the  point  where 
the  crop  begins  to  dilate.  It  runs  into  the  rather  nar- 
row fore  intestine,  which  con  volutes  upon  itself  four 
or  five  times,  and  ends  in  the  hind  intestine,  which  in 
turn  ends  in  the  rectum.  The  intestine  is  called  the 
hind  intestine  from  the  point  where  the  Malpighian  or 
urinary  tubules  enter. 

Naturally  the  structure  and  function  of  the  crop 
and  the  proventriculus  are  matters  of  considerable  in- 
terest in  considering  the  distribution  of  disease  germs 
by  flies.  As  Graham-Smith  points  out,  the  crop  is  first 
distended  with  liquid  food  at  the  beginning  of  a  meal, 


Fig.  14.— Head  of  adult  house  fly;  greatly  enlarged.     (Photograph  by 
N.  A.  Cobb.    Copyright  by  National  Geographic  Society 
of  Washington,  D.  C.) 


Fig.  15. — Head  of  adult  house  fly  from  side;  greatly  enlarged.    (Photo- 
graph by  N.  A.  Cobb.    Copyright  by  National  Geographic 
Society  of  Washington,  D.  C.) 


LIFE  HISTORY  31 

and,  if  after  this  the  fly  continues  to  feed,  the  food 
may  pass  directly  into  the  true  stomach  through  the 
chyle  stomach.  If  the  fly  is  disturbed  before  any  of 
the  food  has  entered  the  stomach,  the  food  which  has 
been  sucked  into  the  crop  is  gradually  passed  into  the 
stomach.  Eventually  the  contents  of  the  crop  get  into 
the  intestine.  The  proventriculus  seems  to  act  also  as 
a  valve  and  be  capable  of  closing  the  orifice  into  the 
stomach  so  that  the  food  shall  all  pass  into  the  crop. 
\Yhen  the  crop  is  fully  distended  it  opens  so  that  food 
can  pass  directly  into  the  stomach,  and  naturally  also 
opens  later  to  allow  the  food  to  pass  from  the  crop 
forward  and  back. 

Careful  observations  made  by  this  author  indicated 
the  rate  at  which  food  passes  from  the  crop  into  the 
intestine,  in  which  he  showed  that,  using  colored  fluid, 
after  three  minutes  the  crop  was  full  of  red  fluid,  but 
none  was  found  in  the  stomach  or  intestine.  After  ten 
minutes  the  fluid  was  just  beginning  to  pass  into  the 
stomach.  After  fifteen  minutes  the  crop  was  still  full 
and  the  upper  third  of  the  stomach  was  full.  After 
two  hours  in  one  case  the  crop  was  still  full  and  the 
upper  three-fourths  of  the  intestine  was  full.  Other 
observations  indicated  that  the  crop  may  remain  full, 
after  a  single  feeding,  for  as  long  as  four  days,  thus 
acting  as  a  storage  reservoir  against  any  possible  scar- 
city of  food. 

Some  interesting  observations  were  also  made  by  the 
same  author  on  the  habits  of  flies  after  feeding  on  dif- 
ferent fluids.  These  observations  were  made  in  cages, 


32    THE  HOUSE  FLY— DISEASE  CARRIER 

and  he  found  that  after  gorging  themselves  they  usually 
climbed  up  the  sides  of  the  cage  and  moved  from  place 
to  place,  often  stopping  to  rub  one  leg  against  another 
or  to  clean  themselves  by  passing  the  legs  over  their 
heads  and  wings.  At  intervals  he  noticed  that  they 
sat  still  and  regurgitated  large  drops  of  liquid  from 
the  tips  of  their  beaks.  He  showed  that  the  drops 
gradually  enlarged  until  they  were  about  equal  in  size 
to  the  head  of  the  fly.  Sometimes  the  drop  was  de- 
posited, sometimes  slowly  withdrawn,  and  this  occurred 
several  times.  When  disturbed,  the  drops  were  de- 
posited or  withdrawn  with  great  rapidity.  Flies  were 
often  seen  to  suck  up  the  drops  deposited  by  other  flies. 
It  is  these  regurgitated  drops  which  make  the  larger 
stains  upon  a  window  covered  with  fly-specks. 

Attention  should  be  called  to  the  shape  of  the  com- 
pound eyes  of  the  fly,  and  it  will  be  noticed  that  they 
are  so  situated  that  a  fly  can  see  in  all  directions  at  the 
same  time. 

Difference  in  Size  of  Adults 

There  is  a  considerable  difference  in  the  size  of  the 
adult  winged  flies,  but  this  by  no  means  signifies  that 
small  adult  flies  grow  into  large  ones.  This  is  a  wide- 
spread popular  fallacy.  The  writer  once  in  his  younger 
days  attended  a  meeting  of  the  Philosophical  Society 
of  Washington  to  listen  to  a  paper  by  the  late  C.  V. 
Riley  on  some  phases  of  insect  life,  in  the  course  of 
which  the  house  fly  was  incidentally  mentioned.  With 
his  entomological  training,  he  was  amazed  in  the  dis- 


LIFE  HISTORY  33 

cussion  which  followed  to  hear  one  of  the  most  emi- 
nent of  America's  scientific  men  (an  astronomer,  by 
the  way)  ask  Professor  Riley,  "It  is  true,  of  course,  is 
it  not,  that  the  little  flies  one  occasionally  sees  on  the 
window-pane  grow  and  become  the  large  flies  that  are 
so  numerous?" 

No  fly,  after  it  issues  from  the  puparium,.  grows  at 
all ;  no  insects  grow  after  the  last  molt ;  in  fact,  insects 
can  grow  only  by  casting  their  skins,  and  none  of  the 
insects  having  what  is  called  a  perfect  metamorphosis 
casts  the  skin  after  reaching  the  imago  or  winged 
stage. 

But  some  typhoid  flies  are  larger  than  others,  and 
the  explanation  is  a  different  one  from  that  of  the 
growth  of  the  winged  form.  The  same  thing  is  seen 
with  other  insects,  and  it  results  as  a  rule  from  the 
amount  of  larval  food ;  certain  larvae  stinted  in  their 
supply  of  food  transform  to  pupae  when  small  and  nat- 
urally become  small  adults.  There  is  a  distinct  con- 
nection with  them,  as  with  human  beings,  in  stint  and 
stunt,  aside  from  the  similarity  of  the  words  and  their 
origin. 

With  the  house  fly,  however,  some  exact  observa- 
tions have  been  made  on  this  point  by  Griffith  (1908) 
and  Packard  (1874).  Griffith  found  that  when  the 
larvae  were  kept  cool  and  the  pupae  warm  all  the  flies 
that  came  out  were  small.  In  fact,  he  found  that  it 
was  a  rule  that  cold  surroundings,  even  with  plenty 
of  food,  produced  small  flies.  And  he  further  states 
that  such  small  flies  are  incapable  of  reproduction.  He 


34    THE  HOUSE  FLY— DISEASE  CARRIER 

points  out  that  small  flies  are  found  at  the  end  of  sum- 
mer when  it  has  become  cooler,  and  also  in  the  early 
spring,  the  latter  having  hatched  late  the  previous  au- 
tumn. The  question  of  the  hibernation  of  flies  will  be 
considered  in  a  later  paragraph,  but  in  this  connection  it 
should  be  stated  that  Doctor  Griffith  secured  repro- 
duction in  the  late  autumn  and  winter,  but  that  all  of 
the  resulting  flies  were  of  small  size,  though  their  lar- 
vae were  kept  at  a  warm  temperature.  The  flies  from 
only  one  of  these  batches  were  of  normal  size,  while 
those  in  one  set  were  "extremely  small,  quite  pigmies ; 
and  these  died  from  no  Apparent  cause,  probably  from 
marasmus,  after  a  month."  He  further  states  that 
from  the  same  batch  of  eggs  he  has  reared  large,  me- 
dium and  small  flies.  Packard  ( 1874)  found  that  those 
larvae  which  were  reared  in  too  dry  manure  were 
nearly  one-half  smaller  than  those  taken  from  the  ma- 
nure heap.  No  direct  warmth  and  the  absence  of  mois- 
ture seemed  to  cause  them  to  become  dwarfed. 

The  error  of  deduction  made  by  the  famous  astron- 
omer was  by  no  means  an  error  of  observation,  as  ap- 
pears from  what  precedes,  but  there  are  found  in  houses 
other  flies  of  entirely  different  species  from  the  house 
fly,  as  will  be  shown  in  another  chapter.  Some  of 
these  are  considerably  smaller,  and  one  of  them,  the 
little  fly  often  seen  on  window-panes  (Homalomvui 
canicularis),  is  very  much  smaller.  In  fact,  as  though 
to  perpetuate  the  error,  the  Germans  call  this  last  spe- 
cies "die  kleine  Stubenfliege" — the  little  room  fly  or 
house  fly. 


LIFE  HISTORY  35 

Summary  of  Duration  of  Life  Round 

In  summarizing  the  duration  of  the  life  round,  we 
find  that  the  writer's  Washington  observations  made 
the  total  life  round  approximately  ten  days,  as  indi- 
cated in  an  earlier  paragraph.  These  were  midsummer 
observations  made  in  August,  1895,  on  the  Depart- 
ment of  Agriculture  grounds  in  the  city  of  Washing- 
ton, but  in  a  warmer  climate  they  may  be  hastened 
even  beyond  this  minimum.  Thus,  in  India  Surgeon 
Major  F.  Smith,  of  the  Royal  Army  Medical  Corps, 
found  at  Benares  that  from  a  collection  of  one  day's 
fresh  droppings  of  three  horses  the  adult  Musca  domes- 
tica  was  obtained  on  the  eighth  day  after  the  laying  of 
the  eggs,  thus  shortening  the  period  considerably. 
Moreover,  Doctor  Hewitt's  minimum  rate  of  growth 
was :  egg,  eight  hours ;  first-stage  larva,  twenty  hours ; 
second-stage  larva,  twenty- four  hours;  third-stage 
larva,  three  days;  pupa,  three  days — a  total  of  eight 
days  and  four  hours,  surely  a  much  shorter  period 
than  often  happens  in  England,  although  the  occa- 
sionally high  summer  temperature  combined  with  the 
moist  climate  of  that  country  may  occasionally  bring 
about  this  shortening.  Mr.  Newstead's  observations 
in  Liverpool,  on  the  other  hand,  show  a  minimum 
period  of  from  ten  to  fourteen  days  and  a  maximum 
of  from  four  to  five  weeks  or  longer. 

Dr.  A.  Griffith,  Medical  Officer  of  Hove,  England 
(a  seaport  on  the  English  Channel),  experimented  with 
house  flies  during  1904-7.  He  gives  as  the  minimum 


36    THE  HOUSE  FLY— DISEASE  CARRIER 

time  in  any  of  his  sets  of  rearings,  which  he  tabulates 
in  Public  Health,  May,  1908,  four  and  one-half  to  six 
days  from  egg  to  pupa,  and  three  and  one-half  days 
from  pupa  to  adult  fly,  a  minimum  for  the  life  round 
of  eight  days.  He  found  great  variations  in  this 
period,  according  to  the  prevailing  temperature. 

Number  of  Generations 

Taking  the  minimum  duration  of  a  generation  in 
Washington  so  far  as  observed  (and  this  must  not  be 
taken  as  the  scientific  minimum,  since  it  depends  upon 
observations  taken  only  during  midsummer  of  a  single 
year),  or  we  will  say  perhaps  a  midsummer  average 
under  Washington  conditions,  and  accepting  Doctor 
Hewitt's  observations  as  to  the  time  elapsing  between 
the  issuing  of  the  adult  flies  and  their  sexual  maturity 
as  being,  perhaps  under  American  conditions,  ten  days, 
we  see  that  there  is  time  for  the  development  of  seven 
generations  between  April  I5th  and  September  loth. 
Flies,  it  is  true,  continue  to  emerge  from  manure  piles 
and  other  breeding  places  much  later  than  September 
loth,  and  in  fact  during  the  season  of  1910  active  lar- 
vse  were  found  as  late  as  the  3Oth  of  November,  while 
on  the  occasional  warm  days  of  that  period  adult  flies 
were  still  active  and  laid  eggs.  The  generations  of 
springtime  and  of  autumn,  however,  are  of  much  slower 
development  than  those  of  midsummer,  so  that  it  is 
probably  safe  to  say  that  there  are  seldom  more  than 
nine  generations  a  year  under  outdoor  conditions  in 
places  comparable  in  climate  to  Washington. 


LIFE  HISTORY  37 

Farther  south,  however,  where  the  summer  is  longer, 
and  particularly  where  the  climate  is  moist,  there  may 
be  more  generations  than  this.  In  India,  for  example, 
where  Surgeon  Major  Smith  made  his  observations 
showing  a  minimum  rate  of  eight  days  to  a  generation 
and  where  the  warm  spell  is  very  long,  an  extraordi- 
nary abundance  of  flies  in  the  autumn,  with  proper 
conditions  of  moisture,  is  a  certainty.  No  wonder 
that  the  punkah  was  invented  in  India!  In  the  same 
way,  as  one  goes  north  the  number  of  generations  per 
year  is  naturally  smaller  and  the  autumnal  abundance 
of  flies  becomes  greatly  lessened  in  consequence. 
Forbes's  assistants  in  Illinois  found  the  life  round  in 
midsummer  to  vary  from  nine  to  fourteen  days. 

Possibilities  in  the  Way  of  Numbers 

This  number  of  generations  has  a  direct  bearing 
upon  the  number  of  flies,  not  only  at  different  periods 
during  the  summer,  but  also  in  the  early  autumn,  since 
there  is,  barring  accidents,  a  constant  and  definite  and 
enormous  increase.  Of  course  some  summers  are 
warmer  than  others  and  some  are  moister  than  others, 
and  upon  these  two  factors,  taken  in  connection  with 
that  of  available  places  for  breeding,  the  number  of 
flies  must  depend. 

Take,  for  example,  the  possibilities  in  Washington, 
and  let  us  estimate — on  the  basis  of  the  survival  of  all 
eggs  and  all  individual  flies — upon  plenty  of  places  for 
the  insect  to  develop  and  for  the  larvae  to  feed,  upon 
an  average  of  ten  days  to  a  generation  in  midsummer 


38    THE  HOUSE  FLY— DISEASE  CARRIER 

(this  period  increasing  in  the  autumn  and  being  greater 
also  in  the  springtime),  and  also  upon  a  period  of  ten 
days  after  emerging  of  the  adult  flies  before  sexual 
maturity  is  gained  (this  point  of  the  duration  of  the 
existence  of  the  adult  fly  before  the  attainment  of  sex- 
ual maturity  has  been  the  weak  element  in  other  cal- 
culations that  have  been  made  of  house  fly  abundance) 
— let  us  start,  then,  on  April  I5th  with  a  single  over- 
wintering fly  which  on  that  day  lays  1 20  eggs,  and  we 
will  have  the  following  table: 

April  1 5th,  the  over-wintering  female  fly  lays  120  eggs. 

May  ist,  120  adults  issue,  of  which  60  are  females. 

May  loth,  60  females  lay  120  eggs  each. 

May  28th,  7,200  adults  issue,  of  which  3,600  are  females. 

June  8th,  3,600  females  lay  120  eggs  each. 

June  2oth,  432,000  adults  issue,  of  which  216,000  are 

females. 

June  30th,  216,000  females  lay  120  eggs  each. 
July  loth,  25,920,000  adults  issue,  of  which  12,960,000 

are  females. 

July  I9th,  12,960,000  females  lay  120  eggs  each. 
July  29th,  1,555,200,000  adults  issue,  of  which  777,600,000 

are  females. 

August  8th,  777,600,000  females  lay  120  eggs  each. 
August  1 8th,  93,312,000,000  adults  issue,  of  which  46,- 

656,000,000  are  females. 

August  28th,  46,656,000,000  females  lay  120  eggs  each. 
September  loth,  5,598,720,000,000  adults  issue,  of  which 

one-half  are  females. 

Such  figures  as  these  stagger  the  imagination.  They 
are  apt  to  make  one  feel  hopeless  at  the  thought  of  at- 
tempting to  exterminate  or  to  hold  in  check  a  creature 


LIFE  HISTORY  39 

with  such  possibilities  of  multiplication ;  but  it  must  be 
remembered  that  in  the  supposed  instance  upon  which 
we  have  figured,  all  of  the  eggs  hatched  and  all  of  the 
progeny  have  survived,  whereas  in  nature  a  fly  has 
many  chances  of  death,  not  only  between  the  egg  and 
the  adult,  but  as  an  adult  before  the  period  of  sexual 
maturity  has  been  reached.  And  it  is  upon  this  period 
which  must  elapse  between  the  issuing  of  a  fly  and  the 
time  when  it  shall  lay  eggs  that  one  of  the  several  ex- 
cellent plans  for  the  warfare  against  this  species  has 
been  based.  It  must  be  remembered,  on  the  other  hand, 
that  in  the  table  we  have  assumed  that  each  female 
has  laid  only  120  eggs,  that  is  one  batch,  while  in 
reality  she  may  lay  four  such  batches.  The  task  of 
estimating  the  possibilities  on  the  larger  basis  is  left 
to  some  reader  who  likes  to  multiply.  Does  not  a  con- 
templation of  these  possibilities,  even  with  all  the  pos- 
sible accidents  of  nature  to  limit  them,  indicate  in  the 
strongest  possible  way,  even  if  the  carriage  of  disease 
by  these  pernicious  creatures  were  not  considered,  the 
necessity  of  an  effort  on  the  part  of  people  to  assist 
nature  in  limiting  a  nuisance  to  humanity? 

Number  by  Actual  Count  in  Relation  to 
Quantity  of  Food 

On  August  9th  in  Washington  a  quarter  of  a  pound 
of  rather  well-infested  horse  manure  was  taken  from  a 
manure  pile,  and  in  it  were  counted  160  larvae  and  146 
puparia.  This  would  make  about  1,200  house  flies  to 
the  pound  of  manure.  This,  however,  cannot  be  taken 


40    THE  HOUSE  FLY— DISEASE  CARRIER 

as  an  average,  since  no  larvae  are  found  in  perhaps  the 
greater  part  of  ordinary  horse  manure  piles.  Neither, 
however,  does  it  show  the  limit  of  what  can  be  found, 
since  on  the  same  date  about  200  puparia  were  found 
in  less  than  one  cubic  inch  of  manure  taken  from  a  spot 
two  inches  below  the  surface  of  the  pile  where  the  lar- 
vae had  congregated  in  very  great  numbers.  This,  as 
stated,  was  in  August  and  the  height  of  the  fly  season 
had  not  yet  been  reached.  Major  N.  Faichnie,  of  the 
Royal  Medical  Corps,  in  the  Journal  of  the  Royal  Med- 
ical Corps  for  November,  1909,  gives  the  result  of  cer- 
tain experiments  with  flies,  indicating  that  in  India  he 
reared  4,000  flies  from  one-sixth  of  a  cubic  foot  of 
trench  ground.  He  also  states  that  he  reared  500 
flies  from  one  dropping  of  human  excreta. 

Further  counts  have  been  made  by  Dr.  W.  B.  Herms, 
of  the  University  of  California  ( 1910) .  Doctor  Herms 
took  four  samples  from  different  parts  of  an  average 
horse  manure  pile  in  Berkeley,  Cal.  (not  near  a  livery 
stable).  The  four  samples  weighed  fifteen  pounds  in 
all  and  contained  by  actual  count  10,282  larvae,  nearly 
all  of  which  were  nearly  or  quite  full  grown.  The 
weight  of  the  entire  manure  pile  was  estimated  at 
1,000  pounds,  and,  at  the  rate  counted,  estimating  that 
possibly  one-third  of  the  pile  was  uninfested,  the  pile 
contained  455,000  and  more  larvae.  Is  it  any  wonder 
that  flies  swarm  near  the  average  stable? 


LIFE  HISTORY  41 

Hibernation 

The  typhoid  fly  apparently  suddenly  disappears  with 
the  first  sharp  frost.  It  will  reappear  later  on  the 
warmest  days.  With  a  great  reduction  of  the  tem- 
perature of  their  breeding  places,  many  larvae  are  killed, 
and  eggs  as  well.  Whether  the  pupae  in  their  tight 
puparia  are  destroyed  by  a  certain  degree  of  cold  does 
not  seem  to  be  known.  The  adult  flies  undoubtedly 
linger  in  warmed  houses  throughout  the  winter,  but 
that  enough  of  them  remain  in  active  condition  in  such 
locations  to  perpetuate  the  species  and  to  start  the  rap- 
idly multiplying  generations  of  the  following  summer 
seems  doubtful.  The  adult  flies  undoubtedly  remain 
dormant  even  in  warmed  dwellings,  and  it  is  altogether 
likely  that  some  of  them  remain  dormant  throughout 
the  winter  months  in  sheltered  but  cold  situations. 
Many  adult  insects  pass  the  winter  in  this  way,  and 
observations  have  been  made  which  indicate  that  this 
is  the  case  with  the  house  fly,  although  as  a  matter  of 
fact  sufficient  attention  has  not  been  paid  in  the  obser- 
vations on  record  of  the  exact  specific  identity  of  the 
flies  in  question.  As  has  been  pointed  out  before,  there 
are  so  many  species  of  flies  which  so  exactly  resemble 
the  typhoid  fly  to  the  macroscopic  eye  that  any  one 
may  be  pardoned  for  stating  that  house  flies  have  been 
seen  tucked  away  carefully  in  cracks,  when  a  micro- 
scopic examination  would  have  shown  that  some  other 
species  was  concerned. 

The  best  observations  on  this  general  subject  which 


42    THE  HOUSE  FLY— DISEASE  CARRIER 

have  been  published  are  those  made  by  Mr.  F.  P.  Jep- 
son,  research  student  in  medical  entomology,  Cam- 
bridge University,  England.  According  to  Mr.  Jepson 
(1909),  when  the  frosts  come  and  the  cold  weather 
begins  in  earnest,  unprotected  flies  are  probably  killed. 
Those  which  have  found  the  shelter  of  some  place  like 
a  kitchen  or  a  restaurant  or  a  bake  house,  where  the  arti- 
ficial temperature  is  sufficient  unto  their  needs,  continue 
to  live  actively;  and  will  even  breed  when  conditions 
are  favorable.  He  states  that  some  flies  possibly  exist 
in  dormant  condition  in  such  protected  localities  as  be- 
hind pictures  and  loose  wallpaper.  He  found  sluggish 
specimens  behind  books  on  a  bookshelf  in  December 
and  January  and  observed  them  for  some  time,  find- 
ing them  in  the  same  positions  and  still  living  a  month 
later.  His  observations  ceased  at  the  end  of  January, 
but  he  saw  no  reason  why  they  should  not  live  on  until 
spring  and  then  begin  to  breed.  In  the  course  of  his 
experiments  he  found  that  the  flies  occurring  at  the 
close  of  the  year  are  much  more  hardy  than  those  oc- 
curring in  summer.  This  fact  was  experimentally 
proved,  as  will  be  shown  later.  He  further  states  that 
one  of  his  friends  found  flies,  presumably  typhoid  flies, 
to  issue  in  large  numbers  from  the  empty  frame  of  an 
old  window  which  was  removed  during  the  winter. 

Jepson  experimented  with  the  early  stages,  and, 
knowing  the  idea  that  possibly  the  puparia  hibernate, 
he  attempted  to  carry  200  pupae  through  the  winter, 
but  without  success. 

The  most  interesting  part  of  his  experimental  work, 


LIFE  HISTORY  43 

however,  was  with  200  flies  captured  in  February  fly- 
ing about  in  the  sculleries  and  kitchens  of  one  of  the 
colleges  at  Cambridge.  They  were  quite  as  active  as 
in  the  summer.  The  kitchens  are  underground,  and 
the  fires  are  kept  up  continuously.  The  temperature 
varied  from  65°  F.  in  the  mornings  to  80°  F.  in  the 
evenings,  and  the  flies,  although  somewhat  sluggish 
in  the  morning,  became  active  when  the  fires  were 
poked  up.  The  200  flies  under  experimentation  were 
transferred  to  a  greenhouse,  which  was  kept  in  a  sim- 
ilar temperature  to  the  kitchens  where  they  were  cap- 
tured, and  were  kept  in  closed  vessels  with  a  supply 
of  moist  bread  beginning  to  ferment.  It  is  worthy  of 
note,  by  the  way,  that  he  found  that  on  several  occa- 
sions the  flies  would  not  lay  their  eggs  upon  bread 
which  had  not  begun  to  ferment.  After  the  flies  had 
been  confined  twenty-four  hours  they  laid  their  eggs, 
and  on  the  following  day  all  of  the  eggs  hatched.  As 
the  bread  became  moldy  the  larvae  avoided  it,  and  were 
transferred  to  other  enclosures  and  fed  upon  stale  bread 
slightly  moistened.  They  fed  until  full  grown,  then 
crawled  away  from  the  moisture  and  transformed  to 
pupae  under  pieces  of  newspaper.  At  a  temperature 
ranging  between  65°  F.  and  75°  F.  in  February,  the 
entire  duration  of  the  life  round  occupied  three  weeks. 

It  thus  appears  that  under  artificial  heat  conditions 
the  typhoid  fly,  given  food  for  its  larvae,  will  continue 
to  breed  almost  as  rapidly  as  during  the  summer  time. 

Mr.  Jepson's  observations  on  the  length  of  life  of 
the  adult  flies  in  the  winter  time  further  .support  the 


44    THE  HOUSE  FLY— DISEASE  CARRIER 

idea  that  the  species  constantly  hibernates  in  this  con- 
dition. Upon  the  emergence  of  the  adults  which  he 
reared  in  confinement  in  February,  they  were  trans- 
ferred to  a  large  net  cage  and  were  kept  alive  success- 
fully for  eleven  and  one-half  weeks.  The  original  flies 
caught  in  the  kitchens  in  February  were  kept  in  cap- 
tivity for  ten  weeks.  How  long  they  had  lived  before 
capture,  of  course,  was  unknown,  but  presumably  since 
the  previous  autumn.  The  question  of  the  length  of 
life  of  the  adult  fly  under  all  conditions  will  be  con- 
sidered in  a  later  paragraph. 

HABITS  OF  THE  ADULT  FLY 

On  issuing  from  its  pupal  sheath,  the  first  impulse 
of  the  adult  fly  is  to  feed.  After  its  rest  in  the  pupal 
condition,  during  which  time  it  has  taken  no  food  and 
has  subsisted  by  the  physiological  consumption  of  the 
fat  cells  stored  up  during  the  last  larval  period,  it  has 
naturally  become  hungry,  and  it  flies  immediately  to  the 
first  point  offering  sustenance.  The  sense  of  smell  of 
the  typhoid  fly  must  be  very  keen,  although  its  selec- 
tion of  attractive  odors  undoubtedly  differs  from  our 
own.  It  is  very  catholic  in  its  choice  of  food — the  milk 
jug  and  the  freshly  baked  custard  pie  are  apparently 
equally  in  favor  with  the  slop  bucket,  the  garbage  pan, 
and  all  sorts  of  unmentionable  filth.  It  knows  the  odor 
of  cooking,  and  it  flies  unerringly  towards  the  nearest 
kitchen,  although  here  the  temperature  of  the  kitchen 
stove  may  attract  it  almost  as  much  as  the  possibility 
of  something  good  to  eat.  As  has  been  shown  in  our 


HABITS  OF  THE  ADULT  FLY  45 

brief  discussion  of  the  mouth  parts  of  the  adult  fly,  its 
food  must  be  liquid,  and  when  it  alights  upon  a  solid 
a  plentiful  flow  of  a  salivary  liquid  enables  it  to  make 
some  slight  impression  and  to  gain  sustenance.  Thus  it 
drinks  as  well  as  eats,  and  liquids  apparently  contain- 
ing little  that  will  help  it  to  exist  are  sought  by  it,  but 
it  especially  prefers  semi-liquid  mixtures.  Every  one 
who  reads  this  book  knows  how  in  the  old  days,  and 
even  now  in  some  places,  the  typhoid  fly  swarmed  or 
swarms  in  a  certain  class  of  public  restaurants  and  in 
poorly  cared-for  eating  places.  The  story  of  the  man 
who  entered  a  dimly  lighted  railway  restaurant  and 
asked  for  "a  piece  of  that  huckleberry  pie"  and  was  in- 
formed that  it  was  not  huckleberry  but  custard,  is  lit- 
erally true.  Dr.  Theobald  Smith  phrased  it  very  hap- 
pily in  a  paper  written  a  few  years  ago  in  the  following 
words :  "When  we  go  into  a  public  restaurant  in  mid- 
summer, we  are  compelled  to  fight  for  our  food  with 
the  myriads  of  house  flies  which  we  find  there  alert, 
persistent  and  invincible."  Doctor  Smith  has  been  very 
fortunate  in  the  choice  of  the  word  "persistent."  The 
typhoid  fly  does  not  seem  to  have  any  common  sense. 
At  one  time  he  is  alert,  to  use  Doctor  Smith's  word, 
and  it  is  impossible  to  catch  him,  but  his  persistence 
even  in  the  face  of  imminent  danger  is  one  of  his  char- 
acteristics which  is  most  impressive.  When  one  lies 
drowsily  in  bed  of  a  summer  morning  with  but  one  fly 
in  the  room,  "persistence"  is  the  only  word  to  apply 
to  its  annoying  return  again  and  again  and  again  to 
the  face  of  the  sleeper  in  spite  of  repeated  slaps.  Here 


46    THE  HOUSE  FLY— DISEASE  CARRIER 

it  is  the  perspiration  which  attracts  the  fly.  It  is 
hungry  and  thirsty  and  wants  food  and  drink. 

The  typhoid  fly  is  a  diurnal  species.  It  rests  during 
the  night.  It  is  not  especially  fond  of  the  bright  sun- 
shine, and  if  one  stays  in  direct  sunlight  he  is  not  often 
troubled  by  it.  But  it  revels  on  the  shaded  porch  and 
in  the  lighted  house  away  from  the  sun's  direct  rays. 
It  flies  into  the  dimly  lighted  stable  in  search  of  places 
to  lay  its  eggs,  but  in  absolute  darkness  and  even  in 
darkness  which  is  not  absolute  it  rests  immovable.  Its 
resting  position  seems  to  be  a  matter  of  indifference 
to  it ;  it  can  sleep  equally  well  on  the  ceiling  or  on  the 
side  wall.  It  does  seem  to  have  some  preference  for 
anything  hanging  perpendicularly,  such  as  an  old-fash- 
ioned rod  supporting  a  candelabrum  or  a  central  gas 
fixture  or  a  window-curtain  string,  and  this  observed 
preference  has  been  taken  advantage  of  by  the  inventors 
of  certain  fly  traps  which  consist  of  a  suspended  strip 
of  sticky  paper. 

Reverting  once  more  to  the  feeding  of  the  adult  fly, 
a  correspondent  whose  name  the  writer  has  unfortu- 
nately forgotten  described  an  instance  where  he  had 
left  a  blood-stain  on  a  slide  at  which  a  house  fly  sub- 
sequently sucked.  On  examining  it  afterwards  under 
the  microscope,  the  fly,  he  found,  had  taken  up  all  of 
the  red  blood  corpuscles  and  had  left  all  of  the  white. 

Flies  are  great  feeders.  Where  food  is  abundant 
they  will  suck  at  it  almost  continuously  or  at  very  brief 
intervals.  As  indicated  elsewhere,  the  alimentary  canal 
is  comparatively  simple,  the  digestive  processes  seem 


HABITS  OF  THE  ADULT  FLY  47 

of  the  simplest  and  the  food  passes  through  the  body 
with  the  greatest  facility. 

Do  Flies  Have  a  Color  Preference? 

Galli-Valerio  (1910)  states  that  the  French  agri- 
cultural journals  have  published  a  statement  that  Fe, 
having  observed  that  flies  do  not  rest  upon  walls  cov- 
ered with  blue  paper,  blue-washed  the  walls  of  his  milk 
stables  and  that  the  flies  then  disappeared,  and  asks 
the  question  whether  a  similar  method  could  be  used 
to  keep  flies  out  of  houses.  He  himself  conducted  ex- 
periments with  a  box  having  glass  walls,  35  X  35  X  35 
cm.  in  size,  and  pasted  on  the  walls  bits  of  paper  all 
the  same  size  but  of  different  colors,  and  afterwards 
introduced  a  certain  number  of  house  flies.  For  sev- 
eral days,  after  turning  the  cage  in  different  positions 
so  as  to  avoid  error  from  other  causes,  he  counted  the 
flies  which  were  standing  on  the  different  colors.  The 
results  were  as  follows : 

Clear  green 18  Dark  green 5 

Rose   17  Red  4 

Clear  yellow 14  Orange   3 

Azure   13  Clear  brown 3 

Clear  red 10  Pale  rose 3 

Dark  gray 9  Very  clear  green 2 

White   9  Blue I 

Dark  red 8  Pale  violet I 

Black   7  Dark  brown i 

Pale  gray 5  Lemon  yellow I 

Dark  yellow 5 

The  observer  noted  that  eighty-seven  flies  stood  on 
the  clear  light  colors,  and  fifty-two  on  the  dark.  Blue 


48    THE  HOUSE  FLY— DISEASE  CARRIER 

was  surely  one  of  the  colors  least  visited,  but  on  the 
contrary  azure  was  one  of  those  most  frequented.  He 
thinks  that  possibly  after  all  it  was  only  a  chance,  but 
is  of  the  opinion  that  Fe's  observation  should  be  the 
basis  of  an  experiment  on  a  large  scale  with  the  same 
ultramarine  blue  which  he  employed.  It  seems  doubt- 
ful, however,  that  a  cold,  hungry  fly  will  be  kept  from 
a  warm,  odoriferous  kitchen  by  the  bluest  of  blue  col- 
ors. 

Fly-specks 

Since,  on  account  possibly  of  the  simplicity  of  the 
digestive  processes  just  referred  to,  pathogenic  bacteria 
and  other  micro-organisms  pass  unchanged  through 
the  alimentary  canal  of  the  typhoid  fly,  the  question  of 
fly-specks  becomes  one  of  great  importance.  Every 
casual  observer  knows  that  they  are  laid  with  great 
frequency,  and  that  when  flies  are  abundant  their 
specks  are  to  be  found  everywhere.  Curiously  enough, 
few  exact  observations  have  been  made  upon  the  fre- 
quency with  which  the  fly  deposits  its  excreta.  Major 
N.  Faichnie,  previously  referred  to,  working  in  India, 
found  that  when  a  fly  is  put  in  a  clean  paper  box  it  passes 
its  excrement  fifty  times  in  twenty-four  hours;  that  is 
to  say,  about  once  every  half  hour;  but  he  neglects  to 
state  whether  there  was  food  in  the  box.  Presumably 
there  was  some  food,  and  also  presumably  there  was 
not  much  of  a  semi-liquid  character.  Cobb  (1910) 
gives  a  table  of  the  intervals  between  defecation  of  a 
well-fed  fly,  together  with  notes  on  the  spores  in  the 
excreta.  One  naturally  infers,  from  the  title  of  the 


HABITS  OF  THE  ADULT  FLY  49 

article,  that  the  fly  in  question  was  a  house  fly,  but 
upon  consulting-  an  important  paper  by  the  same  author 
(1906),  entitled  "Fungous  Maladies  of  the  Sugar 
Cane,"  the  same  table  is  found  printed  on  page  64 
and  the  fly  in  question  is  said  to  be  a  Sarcophagid, 
and  therefore  not  Musca  domestica.  In  his  opening 
paragraph  in  the  1910  article,  Doctor  Cobb  explains, 
"In  some  of  these  paragraphs,  however,  the  statements 
are  inferences  fully  justified  by  experiments  with  very 
similar  species,"  and  this  table  is  evidently  one  of  these 
inferential  statements.  It  is  not  safe  to  state  that  be- 
cause, as  shown  in  the  table,  a  well-fed  Sarcophagid 
fly  will  defecate  on  the  average  once  every  four  and 
one-half  minutes,  from  half  past  nine  until  half  past 
eleven,  a  true  Musca  will  do  the  same.  It  is  by  no 
means  impossible  that  it  will  do  so,  but  unfortunately 
we  have  not  the  proof.  Still  with  this  explanation  it 
will  be  interesting  to  state  that  in  the  interval  between 
9:  35  and  11:26  the  fly  observed  by  Doctor  Cobb  (it 
had  been  fed  at  9 :  23)  made  twenty-three  fly-specks  at 
intervals  varying  from  one  to  fifteen  minutes,  an  av- 
erage of  about  four  and  one-half  minutes ;  and  in  ten 
of  these  twenty-three  specks  Doctor  Cobb  found  spores. 
Herein  lies  one  very  great  danger  from  flies.  Certain 
authors  believe  that  the  danger  from  disease  germs 
that  pass  through  the  fly's  body  in  this  way  is  greater 
than  from  those  that  are  supposed  to  be  carried  from 
foul  substances  on  its  feet. 

With  the  abundance  of  flies  in  the  late  summer,  the 
number  of  fly-specks  becomes  almost  unlimited.     Doc- 


50    THE  HOUSE  FLY— DISEASE  CARRIER 

tor  Cobb  states  that  he  possesses  actual  counts  made 
by  the  use  of  a  little  counter  of  his  own  invention,  but 
that  he  does  not  publish  these  records  for  fear  that  he 
will  be  accused  of  sensationalism.  He  says  that  win- 
dow-panes with  from  1,000  to  10,000  fly-specks  per 
square  foot  are  not  at  all  uncommon,  and  that  from 
ten  to  fifty  per  square  foot  is  a  common  number  in  what 
are  considered  well-kept  homes.  And  this  is  only  in 
places  where  the  dirt  can  be  readily  seen.  He  states 
that  on  neutral-tinted  objects  which  are  not  cleaned  so 
frequently  fly-specks  occur  in  millions.  "On  wallpaper, 
chandeliers,  outside  veranda  posts,  on  cornices,  ceil- 
ings, and  window  blinds,  the  numbers  are  almost  past 
computation."  He  further  shows  that  examination  of 
the  excreta  of  flies  captured  in  the  open  shows  that 
they  contain  a  great  variety  of  spores  in  living  con- 
dition. He  finds  that  the  digestion  of  the  fly  consists 
simply  in  the  absorption  of  those  substances  readily 
soluble  in  its  weak  digestive  fluids  and  the  evacuation 
of  all  others;  therefore  the  fly  is  an  enormous  feeder. 
Doctor  Cobb  states  that  in  a  single  meal  it  frequently 
swallows  nearly  half  of  its  own  weight  of  food.  This 
accounts  for  the  frequency  of  the  fly-specks,  and,  con- 
sidering the  number  of  flies,  for  the  enormous  num- 
ber of  specks. 

Doctor  Graham-Smith,  elsewhere  quoted,  made  a 
few  studies  of  the  number  of  deposits  left  by  flies.  He 
found  that  the  rate  at  which  the  deposits  are  produced 
depends  upon  temperature  and  the  form  of  food,  flies 
being  most  lively  in  hot  weather  or  when  placed  in  a 


HABITS  OF  THE  ADULT  FLY  51 

warm  incubator.  He  fed  three  lots  of  flies  on  syrup, 
milk,  and  sputum,  respectively,  for  several  days,  and 
noted  that  those  fed  on  syrup  produced  an  average  of 
four  and  seven-tenths  deposits  per  fly  per  day,  those 
on  milk  eight  and  three-tenths  and  those  fed  on  sputum 
twenty-seven.  In  the  latter  case  he  states  that  the  feces 
were  much  more  abundant  and  liquid  than  usual,  and 
that  in  fact  the  flies  seemed  to  suffer  from  diarrhea. 
In  another  series  of  experiments  ten  flies  were  given 
a  single  feed  of  milk  and  then  transferred  to  fresh 
cages.  They  deposited  either  by  regurgitation  or  as 
excrement  forty-one  spots  in  the  first  hour,  sixteen  in 
the  second  and  third,  twenty-four  in  the  fourth,  twenty- 
four  in  the  fifth,  and  fifty-nine  in  the  prolonged  inter- 
val between  the  sixth  and  twenty-second  hour.  With 
another  series  of  eleven  flies,  milk  was  always  present 
in  the  cage  so  that  the  flies  could  feed  as  often  as  they 
wished,  and  here  thirty-two  spots  were  made  in  the 
first  hour,  forty  in  the  second  and  third,  ten  in  the 
fourth,  eighteen  in  the  fifth,  and  134  in  the  sixth  to 
the  twenty-second  hour;  making  a  total  of  164  spots 
from  the  ten  flies  that  had  had  but  one  feeding  and 
224  from  the  eleven  flies  which  had  the  milk  contin- 
uously in  their  cage. 

Distance  of  Flight 

Prof.  S.  P.  Langley,  the  late  Secretary  of  the  Smith- 
sonian Institution,  was,  as  every  one  knows,  greatly 
interested  in  the  problem  of  aeronautics,  and  his  ex- 
periments with  flying  machines  heavier  than  air  prac- 


52    THE  HOUSE  FLY— DISEASE  CARRIER 

tically  made  him  the  first  successful  investigator  in  this 
direction,  since  the  Wright  brothers  acknowledge  that 
they  owe  very  much  to  Langley's  scientific  papers  on 
this  subject.  From  his  interest  in  this  direction,  Pro- 
fessor Langley  devoted  certain  grants  from  the  so- 
called  Hodgkins  fund*  to  the  study  of  the  mechanism 
of  flight  of  various  birds  and  insects.  Some  of  the 
results  of  these  studies  have  already  been  published  in 
the  Smithsonian  Miscellaneous  Collections.  During  the 
past  ten  years  a  series  of  these  investigations  have  been 
carried  on  under  Prof.  Robert  von  Lendenfeld  of  the 
University  of  Prague,  and  from  a  report  received  from 
Professor  von  Lendenfeld  by  the  present  Secretary  of 
the  Smithsonian  Institution,  Doctor  Walcott,  which  the 
writer  has  been  permitted  to  see,  it  appears  that,  after 
a  study  of  the  organs  of  flight  in  the  Lepidoptera, 
Hymenoptera,  and  Diptera  by  Messrs.  Hauptmann, 
Groschl,  Ritter,  and  Professor  von  Lendenfeld,  the 
latter  became  convinced  that  of  all  the  forms  of  insects, 
and  indeed  of  all  flying  animals,  the  Diptera  would 
furnish  the  best  models  for  flying  machines.  He  thinks 
that  a  model  built  according  to  this  pattern  should  be 
made  and  experimented  with.  Certain  studies  by  Mr. 
Ritter  on  the  blow  fly,  which  are  at  the  time  of  this 
writing  in  the  hands  of  the  Smithsonian  Institution 
for  publication,  indicate  that  this  insect  and  its  flight 
would  form  the  best  basis  for  a  model. 

This  is  an  interesting  and  important  statement,  since 

*A  bequest  to  the  Smithsonian  Institution  for  the  investigation 
of  the  properties  of  the  upper  air. 


HABITS  OF  THE  ADULT  FLY  53 

it  has  been  made  after  a  long  series  of  comparative 
studies,  and  its  truth  will  readily  be  admitted  by  any 
one  who  has  paid  much  attention  to  the  flight  of  Dip- 
tera.  Cobb,  in  his  paper  on  the  Fungous  Maladies  of 
the  Sugar  Cane,  records  a  number  of  observations  on 
the  flight  of  flies  in  connection  with  the  distribution  by 
the  flies  of  the  spores  of  a  fungous  disease  of  sugar 
cane.  He  states  that  he  never  succeeded  in  tiring  his 
flies  very  perceptibly  if  they  had  a  free  space  to  move 
around  in.  When  confined  in  a  room  they  were  kept 
on  the  wing  for  hours  without  showing  much  fatigue. 
By  dissection  he  showed  that  with  certain  of  the  Sar- 
cophagid  flies  the  thoracic  or  wing  muscles  constituted 
twenty-six  and  two-tenths  per  cent,  of  the  weight  of  the 
fly,  and  that  the  mass  of  the  great  thoracic  muscles  is 
proportional  to  the  apparent  power  of  flight  among  dif- 
ferent flies.  He  records  also  a  remarkable  example  of 
the  power  of  flight  of  one  of  the  larger  flies.  On  a 
voyage  across  the  Mediterranean  from  Algiers  to  Mar- 
seilles, he  observed  a  Dipterous  insect  keeping  pace  with 
the  steamer  "so  accurately  that  it  almost  seemed  as 
if  it  were  joined  to  the  boat  by  some  invisible  rigid 
connection.  The  boat  left  Algiers  at  noon  and  as  long 
as  there  was  any  light  left  by  which  to  observe,  the 
insect  kept  its  place  steadily.  This  was  in  midsummer. 
The  insect  never  made  any  attempt  to  come  aboard. 
The  boat  was  not  particularly  fast,  her  speed  being 
about  thirteen  knots." 

Every  one  who  has  driven  a  fast  team  of  horses  over 
a  road  through  pine  timber  must  have  noticed  the  ex- 


54    THE  HOUSE  FLY— DISEASE  CARRIER 

traordinary  flight  of  the  gadflies  of  the  family  Taban- 
idae,  which  for  hours  will  circle  about  the  horses,  fly- 
ing with  ease  much  more  rapidly  than  the  speed  of  the 
vehicle,  alighting  only  occasionally.  It  is  not  intended 
to  convey  by  these  instances  the  impression  that  it  is 
known  that  the  house  fly  is  at  all  extraordinary  as  a 
flier  among  the  Diptera — in  fact,  when  the  truth  is 
fully  known  it  may  be  shown  to  be  comparatively  a 
weak  flier  among  its  relatives;  but  it  darts  here  and 
there  through  the  air  with  great  speed,  and  if  it  were 
obliged  to  fly  great  distances  the  writer  has  little  doubt 
of  its  ability  to  do  so. 

The  practical  question  involved  in  the  distance  of 
flight,  however,  is  the  one  of  protection  of  food  sup- 
plies at  a  distance  from  fly  breeding  places  which  can- 
not be  controlled.  Will  the  proper  care  of  the  stables 
and  houses  in  a  given  city  square  relieve  the  houses  in 
this  square  from  the  fly  pest  to  a  measurable  degree, 
provided  stables  and  houses  one  square  or  two  squares 
away  remain  uncared  for?  The  situation  must  be 
much  as  it  is  with  mosquitoes,  although  the  house  fly 
is  a  much  stronger  flier  than  any  mosquito.  The  house 
fly  will  seldom  travel  very  much  farther  than  it  has  to 
fly  for  food  and  a  proper  nidus  for  its  eggs,  but  as  a 
matter  of  fact  it  is  very  difficult  to  prove  this.  Fur- 
ther experimental  work  should  be  carried  on  in  this  di- 
rection. 

J.  S.  Hine  (in  lit.)  states  that  in  the  summer  of  1910 
he  made  an  effort  to  determine  the  distance  that  flies 
travel.  At  a  barn  where  he  was  carrying  on  some  work 


HABITS  OF  THE  ADULT  FLY  55 

he  captured  some  350  flies  and  marked  each  one's  wing 
or  thorax  with  a  small  spot  of  gold  enamel.  Flies  so 
marked  were  repeatedly  observed  about  dwellings  from 
twenty  to  forty  rods  from  the  barn  up  to  the  third  day, 
but  in  a  dwelling  house  a  half  mile  away  none  of  the 
marked  specimens  was  detected.  This,  however,  was  a 
very  unsatisfactory  experiment,  because  it  does  not  in 
the  least  show  that  if  the  dwellings  twenty  to  forty 
rods  from  the  barn  had  not  existed  flies  would  not  have 
been  found  in  the  dwelling  half  a  mile  away.  As  Hine 
himself  states,  "It  appears  most  likely  that  the  dis- 
tance flies  may  travel  to  reach  dwellings  is  controlled 
by  circumstances.  Almost  any  reasonable  distance  may 
be  covered  by  a  fly  under  compulsion  to  reach  food  or 
shelter.  Where  these  are  close  at  hand  the  insect  is 
not  compelled  to  go  far,  and  consequently  does  not 
do  so." 

Hewitt  is  of  the  opinion  that  normally  house  flies 
do  not  fly  great  distances,  and  compares  them  to  do- 
mestic pigeons  which  hover  about  a  house  in  the  im- 
mediate neighborhood.  He  states  that  they  are  able 
to  fly,  however,  for  a  considerable  distance  and  can  be 
carried  by  the  wind.  At  one  time  when  he  was  vis- 
iting the  Channel  Islands  he  found  the  house  fly  from 
one  and  one-half  to  two  miles  from  any  house  or  any 
likely  breeding  place  that  he  was  able  to  find.  He 
mentions  some  exact  experiments  made  by  Dr.  M.  B. 
Arnold  at  the  Monsall  Fever  Hospital,  Manchester, 
where  300  flies  were  captured  alive  and  marked  with  a 
spot  of  white  enamel  on  the  back  of  the  thorax.  They 


56    THE  HOUSE  FLY— DISEASE  CARRIER 

were  liberated  in  fine  weather,  and  out  of  the  300  five 
were  recovered  in  fly  traps  at  distances  of  from  thirty 
to  190  yards  from  the  place  of  liberation,  and  all  within 
five  days.  He  further  states  that  he  had  found  them 
at  an  altitude  of  eighty  feet  above  the  ground,  and 
calls  attention  to  the  fact  that  such  a  height  would  fa- 
cilitate their  carriage  by  the  wind. 

An  experiment  made  under  the  direction  of  Prof. 
S.  A.  Forbes,  of  which  he  has  sent  me  a  written  ac- 
count, indicates  that  house  flies  may  spread  naturally 
for  at  least  a  quarter  of  a  mile,  going,  in  one  significant 
instance,  from  the  tuberculosis  hospital  to  the  general 
hospital  of  Cook  County,  Illinois.  House  flies  trapped 
at  one  point  were  sprayed  with  a  chemical  solution  and 
liberated.  Then  flies  caught  on  fly  paper  elsewhere 
were  sprayed  with  another  solution,  the  result  being 
that  those  which  had  previously  been  sprayed  were 
turned  dark  blue  in  color  by  the  second  solution. 

Marking  Flies  for  Experiment 

Professor  Hine  found  that  it  was  a  very  difficult 
matter  to  mark  flies  so  that  they  might  be  recognized 
from  others,  since  they  are  very  sensitive  to  anything 
unusual,  and  any  foreign  substance  on  their  bodies  or 
wings  causes  them  to  act  abnormally.  They  contin- 
ually try  to  remove  the  foreign  substance  and  seem  to 
tire  themselves  out.  He  found  that  many  specimens 
marked  with  the  greatest  care  would  hardly  fly  after 
they  were  marked,  so  that  it  was  easy  in  many  cases  to 
approach  them  and  pick  them  up  with  the  fingers.  He 


HABITS  OF  THE  ADULT  FLY  57 

is  of  the  opinion,  therefore,  that  marked  flies  are  likely 
to  be  abnormal  and  are  not  fit  for  purposes  of  exact 
experimentation.  He  found  that  it  was  impossible  to 
clip  off  the  wing  extremity  and  not  inconvenience  the 
flight. 

On  this  subject  of  marking,  Mr.  J.  P.  Jepson,  of 
Cambridge,  England,  conducted  some  interesting  ex- 
periments during  July  and  August,  1908,  under  the  di- 
rection of  Professor  Nuttall.  He  first  tried  ordinary 
household  flour,  but  the  flies  soon  rid  themselves  of  it. 
This  substance  was  used  on  account  of  the  observation 
that  flies  seen  in  mills  often  seem  quite  white  in  color. 
Rice  starch  powder  was  next  tried,  with  no  success. 
They  were  finally  marked  with  ordinary  colored  black- 
board chalks  which  were  finely  ground  up  in  a  mortar 
and  dusted  on  the  flies  until  they  were  completely  cov- 
ered. They  tried  to  clean  themselves,  beginning  with 
the  eyes,  but  never  succeeded  in  removing  the  chalk 
from  the  upper  portion  of  the  thorax  or  from  the  base 
of  the  wings.  Further  experiments  were  tried  with 
aniline  dyes  either  made  in  the  form  of  a  powder  with 
rice  starch  or  mixed  with  alcohol  in  the  form  of  a 
spray.  Then  again  shellac  was  mixed  with  the  alcohol 
in  order  to  make  the  color  sticky.  In  his  summary 
he  found  that  the  use  of  various  aniline  dyes  did  not 
prove  satisfactory;  with  fuchsine  the  mortality  was 
very  large.  He  found  that  dusting  with  rice  starch 
powder  and  then  spraying  with  shellac  and  alcohol  give 
an  excellent  color,  but  decided  that  the  flies  must  be 
allowed  to  clean  their  eyes  before  spraying  and  that 


58    THE  HOUSE  FLY— DISEASE  CARRIER 

the  spray  must  be  thinly  applied.  The  best  result 
reached  by  this  method  was  ten  days.  The  reverse, 
namely,  spraying  with  alcohol  and  shellac  and  then 
dusting  with  rice  powder,  was  satisfactory  where  the 
shellac  was  not  applied  too  thickly.  Colored  chalks 
gave  very  satisfactory  results,  yellow  and  brick  red 
being  the  best ;  the  yellow  lasting  for  nine  days  and  the 
brick  red  for  twenty  days. 

Length  of  Life  of  the  Adult 

It  seems  that  in  midsummer  the  adult  flies  do  not 
live  long,  and  it  is  extremely  difficult  to  keep  them 
for  any  length  of  time  in  an  enclosure,  which,  of  course, 
is  the  only  true  way  of  ascertaining  exact  age.  At  this 
time  of  the  year,  flies  die  rapidly  in  confinement.  In 
June,  1898,  the  writer  was  unable  to  keep  alive  flies 
collected  at  large  and  placed  under  a  gauze  enclosure 
three  feet  cube  for  more  than  three  days,  but  of  course 
this  experiment  meant  nothing,  since  the  age  of  the 
flies  collected  was  not  known.  Mr.  Hine  is  convinced 
that  flies  do  not  live  a  great  many  days  in  warm  sum- 
mer weather.  Marked  flies  in  his  experiments  in  Au- 
gust were  not  to  be  found  after  the  third  day,  and  in 
his  experiments  with  individuals,  in  confinement  with 
all  necessary  food,  he  was  unable  to  keep  them  alive  for 
more  than  twelve  days.  He  mentions  an  instance  where 
on  a  farm  at  Ira,  Ohio,  a  pile  of  infested  manure  at 
the  barn  was  hauled  up  and  spread  in  a  field  a  quarter 
of  a  mile  away  on  August  I5th;  the  occupants  of  the 
house  stated  that  there  was  a  notable  reduction  in  the 


HABITS  OF  THE  ADULT  FLY  59 

number  of  flies  by  August  2Oth.  Major  N.  Faichnie, 
referred  to  above,  in  experimenting  with  flies  in  India 
in  the  summer,  found  that  they  lived  eleven  days  only. 
Mr.  Jepson,  in  his  notes  on  the  breeding  of  the  com- 
mon house  fly  during  the  winter  months,  incidentally 
mentions  the  fact  that  during  the  summer  of  the  pre- 
vious year  (1908)  in  no  case  was  he  able  to  keep  flies 
alive  for  more  than  three  weeks,  and  then  only  with  a 
few  individuals;  whereas,  as  previously  stated,  flies 
reared  during  the  winter  were  kept  alive  for  eleven  and 
one-half  weeks,  and  flies  caught  in  kitchens  in  Febru- 
ary were  kept  alive  for  ten  weeks  and  had  presumably 
been  living  since  the  previous  autumn. 

If  we  take  Jepson's  statement  of  three  weeks  as  be- 
ing the  probable  limit  of  the  life  of  the  adult  fly  in 
midsummer,  and  if  we  conclude,  as  we  must,  that  the 
average  life  at  that  period  is  much  shorter  than  this, 
it  becomes  evident  from  what  will  be  stated  in  the  fol- 
lowing paragraph  that  after  the  female  fly  has  laid  her 
eggs  in  summer  she  has  not  much  longer  to  live.  The 
plain  inference  from  this  will  naturally  be  that  the  hi- 
bernating flies  in  the  winter  time  are  probably  for  the 
most  part  females  which  have  not  laid  their  eggs.  Un- 
fortunately  for  the  conclusions  just  stated,  Doctor 
Hewitt  records  the  fact  that  he  has  kept  flies  in  cap- 
tivity in  the  summer  time  for  seven  weeks,  while  Grif- 
fith (1908)  was  able  to  keep  a  male  sixteen  weeks. 

Ficker  (1903),  in  an  account  of  experiments  carried 
on  between  June  and  October,  states  that  he  kept  flies 
alive  in  confinement  for  four  weeks,  feeding  them  on 


60    THE  HOUSE  FLY— DISEASE  CARRIER 

sugar,  bread,  water,  or  milk.  Unfortunately  he  does 
not  give  the  exact  dates  of  this  particular  observation, 
and  it  may  have  been  on  an  October  generation,  which 
would  have  hibernated. 

Time  Elapsing  Betiveen  the  Issuing  of  the  Adult  and 
the  Period  of  Sexual  Maturity 

The  practical  value  of  the  determination  of  this 
period  is  very  great.  If  an  adult  female  fly  can  be 
destroyed  before  she  lays  her  eggs,  we  will  have  killed 
not  only  the  actual  fly,  but  120  to  600  potential  flies 
due  in  a  very  short  time,  and  if  this  female  fly  can  be 
caught  in  the  early  spring  the  table  on  an  earlier  page 
will  indicate  that  instead  of  performing  a  very  simple 
act  we  have  apparently  saved  the  world  from  almost 
a  calamity.  From  this  can  be  seen  the  value  of  fly 
traps.  Of  course  the  destruction  of  breeding  places 
is  very  important,  but  traps  for  adult  flies  are  by  no 
means  to  be  despised  when  we  have  this  idea  in  view ; 
and  the  use  of  fly  traps  in  the  early  part  of  the  season 
becomes  obviously  all-important.  The  destruction  of 
hibernating  flies  is  equally  of  value ;  but  these  subjects 
will  be  considered  in  the  chapter  on  remedies. 

So  far  as  the  writer  knows,  the  only  observers  who 
have  paid  any  attention  to  this  very  important  point 
of  the  period  elapsing  before  sexual  maturity  are 
Hewitt  (1910)  and  Griffith  (1908).  Hewitt  states 
that  he  found  flies  become  sexually  mature  in  ten  to 
fourteen  days  after  emergence  from  the  pupal  state, 
and  that  four  days  after  copulation  they  begin  to  de- 


HABITS  OF  THE  ADULT  FLY  61 

posit  their  eggs;  that  is  to  say,  from  the  fourteenth 
day  from  the  time  of  their  emergence.  The  experi- 
mental data  upon  which  this  statement  is  based  are  not 
given  in  the  paper  in  question,  and  the  writer  there- 
fore wrote  to  him  for  a  transcript  of  his  record,  from 
which  it  appears  that  the  flies  under  observation 
emerged  between  August  2ist  and  August  28,  1907. 
They  were  given  fresh  horse  manure  daily,  and  accu- 
rate thermometrical  readings  were  recorded  for  each 
of  the  following  days.  Not  until  September  4th  was 
copulation  observed,  and  on  September  Qth  larvae  were 
found  in  the  manure. 

Doctor  Griffith,  in  his  observations  at  Hove,  found 
that  the  female  flies  oviposited  ten  days  after  issuing 
from  the  puparia,  and  that  they  could  lay  new  batches 
of  eggs  at  intervals  of  from  ten  to  fourteen  days  until 
four  batches  have  been  laid. 

It  seems  to  the  writer  that  this  period  between  issu- 
ance and  sexual  maturity  must  surely  be  shorter,  and 
perhaps  much  shorter,  under  midsummer  conditions  and 
in  the  freedom  of  the  open  air,  than  that  indicated  by 
Hewitt  and  by  Griffith.  Breeding-cage  observations 
are  never  quite  conclusive. 

So  great  is  the  practical  importance  of  this  point, 
as  already  shown  and  as  will  be  elaborated  later,  that 
the  most  careful  experimental  work  should  be  under- 
taken under  all  sorts  of  circumstances  and  in  very 
many  different  localities. 


II 

THE  NATURAL  ENEMIES  OF  THE  TYPHOID 

FLY 

AS  with  every  other  living  creature,  nature  makes 
its  own  effort  to  limit  the  abundance  of  the  fly 
under  consideration,  and  the  extraordinary  facility  for 
multiplication  which  the  fly  possesses  is  in  turn  the  re- 
sult of  the  instinctive  effort  of  the  organism  to  main- 
tain its  status  in  spite  of  the  numerous  enemies  which 
confront  it.  The  natural  enemies  of  the  house  fly  be- 
gin with  the  acme  of  the  vertebrate  series  (man  him- 
self) and  end  with  the  lower  forms  of  plant  life,  and  we 
will  begin  our  consideration  of  these  agencies  with 
the  latter  forms. 

FUNGOUS  DISEASES 

In  the  autumn  it  is  a  matter  of  common  observation 
that  many  flies  in  houses  and  on  the  windows  become 
sluggish  and  frequently  die  in  such  positions.  The 
sluggishness  may  be  accounted  for  in  a  measure  by  the 
advent  of  cold  weather,  and  as  a  matter  of  fact  cold 
weather  frequently  drives  indoors  other  species  of  flies 
of  a  more  sluggish  nature  than  the  house  fly.  In  this 
way  the  so-called  cluster  fly  (Pollenia  rudis),  a  rather 
sluggish  species,  which  will  be  referred  to  in  another 
chapter,  is  frequently  found  in  houses  in  the  autumn. 

62 


NATURAL  ENEMIES  63 

But  the  principal  cause  of  the  sluggishness  on  the  part 
of  the  house  fly  in  the  autumn  is  the  attack  of  fungous 
diseases.  Sometimes  they  are  found  to  be  dead  without 
any  evidence  of  the  cause  of  death.  Later  they  are 
seen  to  be  surrounded  by  a  white  fungus  growth. 

There  is  a  group  of  fungi  belonging  to  the  En- 
tomophthorese,  many  of  which  are  parasitic  upon  in- 
sects. There  are  several  genera  in  this  group,  but  the 
only  one  which  need  be  considered  at  present  is  the 
genus  Empusa.  The  fungi  of  this  group  have  been 
studied  by  Dr.  Roland  Thaxter  of  Harvard  University, 
and  it  is  from  his  writings  that  the  following  state- 
ments have  been  drawn. 

The  infection  of  insects  by  these  fungi  results  from 
contact  with  a  spore  which,  adhering  to  the  insect,  en- 
ters its  body  by  means  of  a  fungous  thread  known  as 
a  hypha.  The  exact  method  of  the  entrance  of  the 
hypha  is  not  known,  but  it  must  be  through  the  thin- 
ner membrane  connecting  the  body  segments  and  the 
leg  joints,  or  through  the  breathing  pores.  It  has  been 
suggested  that  the  spores  may  be  eaten,  but  Thaxter 
thinks  that  this  is  not  the  usual  means  of  introduction, 
since  experiments  that  he  has  made  contradict  it,  and 
he  finds  that  as  a  rule  the  digestive  tract  during  life 
does  not  seem  to  be  penetrated  by  the  fungus.  After 
one  of  these  hyphae  has  entered  the  body  of  the  insect 
it  develops  with  some  rapidity  at  the  expense  of  the 
softer  tissues.  It  multiplies,  not  by  branching  or  by 
continuing  to  grow,  but  by  the  formation  of  short, 
thick  fragments  of  various  sizes  and  shapes  that  are 


64    THE  HOUSE  FLY— DISEASE  CARRIER 

continually  reproduced  by  budding  or  division  until 
the  insect  is  more  or  less  completely  filled  with  them. 
These  fragments  are  called  hyphal  bodies.  They  con- 
tain a  highly  concentrated,  fatty  protoplasm  and  are 
capable  of  subsequent  and  often  very  extended  develop- 
ment. 

When  the  mass  of  these  bodies  has  been  completed 
and  the  death  of  the  insect  attacked  has  occurred,  the 
fungus  may  proceed  at  once  to  the  completion  of  its 
development  under  proper  conditions  of  temperature 
and  moisture,  but  if  these  conditions  are  absent  a  rest- 
ing stage  ensues  in  which  the  contents  of  each  hyphal 
body  becomes  Surrounded  by  a  single  wall  which  in- 
creases in  thickness  as  the  resting  stage  continues.  The 
fungus  may  remain  dormant  in  this  condition  for  i 
considerable  period.  Doctor  Thaxter  has  observed  the 
hyphal  bodies  germinating  after  several  weeks,  and 
thinks  that  they  probably  retain  their  vitality  for  a 
much  longer  period,  and  may  perhaps  hibernate  under 
certain  circumstances. 

When  a  moist  atmosphere  and  a  sufficiently  high 
temperature  come  they  germinate  with  great  rapidity. 
With  the  common  house  fly  fungus  (Empusa  musca) 
a  slight  change  in  the  amount  of  atmospheric  moisture 
is  sufficient  to  bring  about  germination.  This,  accord- 
ing to  Thaxter,  is  very  noticeable  on  the  seashore, 
where  slight  changes  of  the  wind  from  the  water  or 
from  the  shore  bring  about  a  very  rapid  and  noticeable 
effect  upon  the  flies  thus  parasitized  when  watched  in 
the  ordinary  atmosphere  of  the  house.  With  other 


NATURAL  ENEMIES  65 

species  of  Emptisa  attacking  other  insects,  a  much 
greater  degree  of  moisture  is  necessary,  and  certain 
forms  occur  only  in  very  moist  situations. 

In  germinating,  each  hyphal  body  or  resting  spore 
sends  out  one  or  more  hyphse,  which  grow  with  great 
rapidity,  but  the  manner  of  this  germination,  together 
with  the  subsequent  development  of  the  resulting  hy- 
phae,  varies  considerably  with  different  species  and  un- 
der different  conditions.  In  the  simplest  case  a  single 
hypha  thus  produced  may  grow  directly  to  the  outer 
air  and  then  produce  a  single  conidium  or  set  of  con- 
idia.  In  other  cases  a  single  hypha  may  branch  indefi- 
nitely, each  final  branch  bearing  a  conidium  or  conidia. 
This  usually  happens  where  the  conditions  of  growth 
have  been  very  favorable,  and  the  complex  may  be 
found  side  by  side  with  the  more  simple  form. 

The  conidium  or  spore  is  formed  by  budding  from 
one  of  these  hyphse,  which  in  this  case  is  called  a  con- 
idiophore.  This  bud  increases  in  size  and  becomes 
separated  from  the  conidiophore  by  a  cross-partition. 
Within  the  mother  cell  thus  formed  is  developed  a 
single  spore.  When  this  cell  increases  in  size  by  the 
absorption  of  water,  the  wall  of  the  mother  cell  be- 
comes separated  from  that  of  the  conidium  and  some- 
times to  such  an  extent  that  the  conidium  is  seen  float- 
ing free  in  the  large  spherical  mother  cell.  Finally  by 
a  rupture  the  conidium  is  discharged  violently  into  the 
air,  often  for  a  considerable  distance.  With  Empusa 
muscce,  the  conidia  are  bell-shaped  or  nearly  spherical, 
with  a  broad  base  and  a  measurably  pointed  apex, 


66    THE  HOUSE  FLY— DISEASE  CARRIER 

They  contain  usually  a  large  oil  globule  and  are  sur- 
rounded after  discharge  by  a  mass  of  protoplasm. 

If  the  conidium  when  discharged  has  come  in  con- 
tact with  a  suitable  host  insect,  it  adheres  to  it  and  sends 
out  a  hypha  of  germination  which  enters  its  body  as 
just  described.  Secondary  conidia  are  formed  as  a 
provision  for  further  dissemination  in  case  the  primary 
spore  has  fallen  on  a  substance  unsuited  to  its  proper 
development.  With  Empusa  musca  the  secondary  con- 
idia are  like  the  primary,  or  more  commonly  they  are 
sub-ovoid,  small,  round  at  the  apex,  and  formed  by 
direct  budding  from  the  primary  form.  These  also  are 
discharged,  but  are  apparently  better  suited  to  resist 
unfavorable  conditions  than  the  primary  ones,  and 
probably  retain  their  power  cf  germination  much 
longer. 

There  is  also  another  morphological  character  of 
these  fungi — the  formation  of  simple  hyphae  which  pro- 
ject out  beyond  the  conidiophores.  When  they  reach 
in  the  direction  of  the  material  upon  which  the  de- 
stroyed insect  stands  they  attach  the  body  to  it,  and 
are  then  called  rhizoids.  When  they  stick  out  in  any 
other  direction,  however,  they  seem  to  be  functionless 
and  are  called  cystidia  or  paraphyses.  The  hyphae  of 
attachment  or  rhizoids  may  be  simple  or  variously 
branched,  and  their  germination  may  be  variously 
modified  into  an  extended  sucker.  They  do  not  seem 
to  enter  into  soft  substances,  and  their  adhesion  is  ap- 
parently due  to  the  presence  of  a  viscous  secretion. 
They  are  produced  with  great  rapidity,  appearing  often 


NATURAL  ENEMIES  67 

before  the  host  is  dead,  and  increase  greatly  in  number 
with  the  appearance  of  the  conidiophores. 

This  will  suffice  perhaps  for  a  general  account  of  the 
development  of  these  curious  parasitic  fungi.  Empusa 
muscce  Cohn.,  one  of  the  most  abundant  of  them,  at- 
tacks the  house  fly,  and  also  certain  other  large  flies, 
such  as  the  blow  flies  and  many  flower  flies.  It  was 
first  described  by  DeGeer  in  1782,  and  has  since  been 
carefully  studied  by  many  observers.  It  is  almost  as 
universal  as  the  house  fly  itself,  and  is  the  only  Em- 
pusa known  south  of  the  Equator.  As  a  rule,  accord- 
ing to  Thaxter,  the  species  is  found  about  houses,  usu- 
ally within  them,  and  occurs  in  great  abundance  from 
late  June  until  late  in  the  autumn.  It  seems  altogether 
likely  that  the  majority  of  the  deaths  of  flies  in  the  late 
autumn  are  caused  by  this  species.  In  England,  ac- 
cording to  Hewitt,  it  is  found  from  about  the  begin- 
ning of  July  to  the  end  of  October,  usually  indoors. 
In  Washington  the  epidemic  ceases  in  December. 

It  is  not  yet  known  how  this  fungus  lasts  over  from 
one  year  to  another.  Mycologists  have  never  grown  it 
in  artificial  cultures,  and  there  is  evidently  much  yet 
to  be  learned  about  many  important  points  in  its  life 
history.  Much  experimental  work  has  been  done  with 
the  fungus  diseases  of  other  injurious  insects,  particu- 
larly with  those  of  forms  injuring  cultivated  crops, 
but  no  striking  large-scale  results  of  value  have 
been  obtained.  It  is  possible  that  something  practical 
can  be  gained  from  a  close  and  prolonged  study  of  this 
disease  of  the  house  fly,  and  it  is  interesting  to  note 


68    THE  HOUSE  FLY— DISEASE  CARRIER 

that  the  city  of  London  local  government  board  on 
public  health  and  medical  subjects  is  now  aiding  Dr. 
Julius  Bernstein  in  a  detailed  investigation  of  the  life 
history  of  Empusa  musca  and  in  an  attempt  to  cultivate 
it  in  artificial  media,  with  the  object,  if  possible,  of  em- 
ploying these  cultures  to  destroy  flies  on  a  large  scale. 

Two  other  species  of  Empusa  are  recorded  by  Thax- 
ter  as  developing  in  the  typhoid  fly.  These  are  E. 
sphcerosperma  (Fres.)  Thaxter  and  E.  amcricana 
Thaxter.  E.  spharosperma  is  peculiar  for  the  great 
diversity  of  its  hosts,  since  it  destroys  insects  of  all  or- 
ders except  that  to  which  the  grasshoppers  belong.  It 
is  a  very  common  form  and  often  produces  very  con- 
siderable epidemics  among  insects.  It  is  recorded  as 
destroying  the  clover  weevil  in  great  numbers  on  one 
occasion  near  Geneva.  N.  Y.,  by  Dr.  J.  C.  Arthur,  and 
in  1909  produced  an  extraordinary  epidemic  in  the 
same  insect  in  the  vicinity  of  Washington,  D.  C. 

As  it  happens,  an  allied  insect,  probably  accidentally 
imported  from  Europe,  is  causing  great  damage  at  the 
present  time  in  the  alfalfa  fields  in  Northeastern  Idaho. 
Prof.  F.  M.  Webster  of  the  Bureau  of  Entomology  at 
Washington  immediately  conceived  the  idea  of  attempt- 
ing to  introduce  this  fungus  from  Washington  into 
Idaho,  in  the  hope  that  it  would  attack  the  alfalfa 
weevil.  Owing  to  the  dry  climate  out  there,  however, 
the  experiment  failed;  the  conidia  would  not  develop, 
and  it  would  seem  very  difficult  if  not  impossible  to 
produce,  artificially,  moisture  conditions  which  will  en- 
able alfalfa  growers  to  handle  this  disease  practically. 


NATURAL  ENEMIES  69 

The  only  record  of  the  attack  of  this  species  on 
Musca  domestica  is  by  Brefeld.  Empusa  americana 
seems  confined  to  large  flies,  like  the  house  fly,  the 
blow  flies  and  the  like.  Doctor  Thaxter  states  that  it 
is  frequently  met  with  from  June  to  October  on  the 
borders  of  woods  near  brooks  or  in  shrubbery  about 
houses.  The  fly  is  generally  found  fixed  to  the  under, 
or  rarely  the  upper,  sides  of  leaves  or  bare  twigs  a  few 
feet  above  the  ground.  It  occurs  in  New  England  and 
North  Carolina.  The  rhizoids  or  attaching  hyphse,  in- 
stead of  growing  out  in  the  form  of  numerous  scat- 
tered threads,  are  developed  in  an  even  layer  around  the 
insect's  body,  forming  with  the  conidiophores  a  con- 
tinuous mat-like  covering,  which  often  becomes  dark 
rust  colored  on  exposure  to  the  weather. 

These  are,  so  far  as  known,  the  only  true  botanical 
enemies  of  the  house  fly.  Of  course,  breeding  as  it 
does  in  fermenting  organic  matter  and  in  the  dirtiest 
and  filthiest  locations,  and  frequenting  such  situations 
as  it  does  in  search  of  food,  it  carries  upon  its  body, 
and  within  its  alimentary  canal  for  the  brief  period 
which  it  takes  for  its  food  to  pass  through,  any  num- 
ber of  spores  of  fungi  and  of  bacteria,  but  it  is  prob- 
able that  nearly  all  of  these  are  carried  accidentally 
by  the  fly  and  do  it  no  harm.  Many  species  of  many 
genera  of  fungi  and  bacteria  have  been  cultivated  upon 
sterilized  plates  upon  which  flies  caught  haphazard 
have  been  allowed  to  walk  and  which  they  have  been 
allowed  to  speck,  but  as  just  stated  these  are  probably 
innoxious  to  the  fly  itself.  From  the  observations  of 


70    THE  HOUSE  FLY— DISEASE  CARRIER 

Mr.  H.  T.  Giissow,  Dominion  Botanist  of  Canada, 
quoted  by  Hewitt,  the  fungi  reared  in  this  way  have 
numbered  seven  species,  while  the  bacteria  have  num- 
bered eleven  species. 

PROTOZOAN  ENEMIES  OF  THE  HOUSE  FLY 

Certain  microscopic  protozoa  of  the  group  Flagel- 
lata  have  been  found  in  the  alimentary  canals  of  vari- 
ous insects,  and  one  species  known  as  Herpetomonas 
muscce  domestic^  has  been  found  in  the  intestine  of 
the  house  fly.  The  genus  to  which  it  belongs  is  said 
by  Calkins  to  be  the  most  primitive  and  least  changed 
from  the  free-living  forms  of  the  flagellated  intestinal 
parasites.  It  is  a  general  parasite  of  flies  of  very  wide 
distribution.  It  was  carefully  studied  by  Prowazek  in 
1904  and  by  Captain  W.  S.  Patton  of  the  Indian  Med- 
ical Service  in  1908  and  1909. 

Patton  found  that  in  Madras,  India,  about  one  hun- 
dred per  cent,  of  the  flies  caught  in  the  bazaar  meat 
shops  are  infected  with  this  parasite,  and  he  made  an 
exhaustive  study  of  its  life  history  which  continued 
for  more  than  a  year.  He  found  that  it  exists  in  three 
stages  which  he  calls  the  preflagellate,  the  flagellate 
and  the  postflagellate.  The  first  stage  is  usually  found 
in  the  midgut,  the  parasites  lying  in  masses  within  the 
peritracheal  membrane.  They  are  round  or  slightly 
oval  bodies  of  very  minute  size,  which  multiply  by 
simple  longitudinal  division  or  by  multiple  segmenta- 
tion so  that  a  large  number  is  formed  in  a  short  time. 
The  flagellate  stage  is  characterized  by  the  projection 


NATURAL  ENEMIES  71 

of  a  single  stout  filament.  In  this  stage  it  elongates 
and  divides  later  by  simple  longitudinal  division.  In 
the  postflagellate  stage  the  organism  shortens  in  length 
and  eventually  loses  its  filament. 

Whether  the  presence  of  these  intestinal  parasites 
affects  the  vitality  of  the  fly  is  not  mentioned,  nor  is  it 
understood  whether  they  can  be  transmitted  to  any 
other  animal. 

Since  the  typhoid  fly  does  not  bite,  it  seems  likely 
that  such  a  transfer  does  not  take  place.  It  is  inter- 
esting to  note,  however,  that  a  parasitic  flagellate  of 
the  same  genus,  namely,  Herpetomonas  donovani,  is 
the  causative  organism  of  the  tropical  disease  known 
as  kala  azar,  characterized  by  an  enlargement  of  the 
spleen,  by  irregularly  recurrent  fevers,  anaemia  and 
emaciation,  usually  resulting  in  death,  and  that  Cap- 
tain Patton  has  discovered  that  the  same  parasite  un- 
dergoes a  transformation  in  the  intestine  of  a  bedbug 
(Cimex  rotundatus)  in  India,  confirming  a  suggestion 
made  with  reasons  by  L.  Rogers,  who  had  previously 
discovered  the  flagellated  stage  of  the  parasite.  When 
the  blood  of  a  kala  azar  patient  is  sucked  into  the  ali- 
mentary canal  of  the  bedbug  the  parasites  are  liberated 
by  the  digestive  process  and  begin  to  develop  from 
the  second  to  the  fifth  day.  There  is  no  evidence  that 
the  bedbugs  are  infected  except  from  human  beings, 
and  there  is  no  scientific  proof  that  human  victims  ac- 
quire the  disease  from  the  bugs. 

Another  flagellate  genus,  Crithidia,  is  found  in  the 
intestinal  tract  of  certain  flies,  and  one  of  them  has 


72    THE  HOUSE  FLY— DISEASE  CARRIER 

also  been  given  the  specific  name  Mnsca  domestic^  by 
H.  Werner. 

NEMATODE  PARASITES  OF  THE  TYPHOID  FLY 

The  nematodes,  or  thread-worms,  have  long  been 
subjects  of  observation.  They  are  greatly  elongated, 
thread-like  organisms,  frequently  of  considerable  size ; 
for  the  most  part  laying  eggs,  but  in  rare  cases  bearing 
living  young.  The  younger  stages  or  larvae  of  most 
of  them  have  a  different  habitat  from  that  of  the  adult 
worm.  Some  of  them  develop  in  damp,  muddy  earth, 
migrating  finally  to  lead  a  parasitic  life  within  some 
animal ;  some  are  parasitic  in  plants.  The  old  time  super- 
stition that  a  horse-hair  when  left  in  water  for  a  suffi- 
cient length  of  time  becomes  a  living  worm  arises  from 
observations  upon  some  of  the  largest  nematodes.  Very 
many  insects  are  parasitized  by  the  worms  of  this  group. 

H.  J.  Carter,  in  Bombay,  in  November,  1859,  while 
examining  the  head  of  a  common  house  fly,  noticed 
that  two  nematode  worms  came  out  of  it.  Later,  in 
July,  1860,  he  discovered  that  on  the  average  about 
every  third  fly  in  Bombay  contained  from  two  to 
twenty  or  more  of  these  worms,  which  were  chiefly 
to  be  found  in  the  proboscis,  though  occasionally  oc- 
curring among  the  soft  tissues  of  the  head  and  hinder 
part  of  the  abdomen.  He  described  them  as  bisexual, 
mature,  and  nearly  all  of  the  same  size.  He  placed 
them  in  the  genus  Filaria,  and  described  them  as  Filaria 
muscc?  in  the  Annals  and  Magazine  of  Natural  History, 
Vol.  VII,  pages  30-31. 


NATURAL  ENEMIES  73 

Other  observers  have  studied  this  parasitic  worm, 
which  is  now  placed  in  the  genus  Habronema.  Hewitt, 
in  England,  after  dissecting  many  hundreds  of  flies, 
found  only  two  specimens  of  this  parasite.  He  feels 
certain  that  the  one  found  in  England  is  the  same  as 
the  one  found  by  Carter  in  India. 

The  same  species  occurs  in  the  United  States  and 
has  received  some  attention  from  Dr.  B.  H.  Ransom, 
of  the  Bureau  of  Animal  Industry  of  the  U.  S.  De- 
partment of  Agriculture  at  Washington.  Doctor  Ran- 
som has  very  kindly  given  the  writer  the  following 
note,  hitherto  unpublished,  which  is  sufficiently  interest- 
ing to  print  in  full : 

"Referring  to  Habronema  musca,  this  parasite  seems 
to  be  very  common  in  the  house  fly.  Out  of  thirty- four 
flies  examined  between  June  loth  and  July  nth,  most 
of  them  caught  in  the  laboratory  of  the  Zoological  Di- 
vision, the  remainder  bred  from  horse  manure  obtained 
at  the  Experiment  Station  of  the  Bureau  of  Animal 
Industry,  Bethesda,  Md.,  nine  were  infested.  The 
number  and  distribution  of  the  parasites  in  these  nine 
flies  were  as  follows : 

1.  Five  in  the  proboscis. 

2.  Six  in  the  head  and  proboscis,  one  in  the  thorax. 

3.  One  in  the  head. 

4.  Two  in  the  head. 

5.  Five  in  the  head. 

6.  Two  in  the  head. 

7.  One  in  the  head. 

8.  One  in  the  abdomen. 

9.  Two  in  the  thorax. 


74    THE  HOUSE  FLY— DISEASE  CARRIER 

"Twenty-six  dipterous  larvae  (species  not  deter- 
mined) from  horse  manure  which  were  examined  for 
the  presence  of  nematodes  were  all  free  from  infection 
with  H.  muse  a.  Thirteen  larvae  of  Musca  dorncstica 
and  several  pupae  were  examined  with  negative  results. 
These  were  bred  from  house  flies  confined  in  a  dish 
with  horse  manure  which  had  previously  been  boiled 
to  destroy  any  fly  larvae  or  nematodes  which  might 
have  been  present.  That  some  of  the  flies  were  infested 
with  Habronema  was  determined  by  examining  a  num- 
ber after  oviposition  had  occurred.  An  undersized 
male  which  developed  in  the  culture  just  referred  to, 
the  only  adult  that  was  obtained  in  this  culture,  was 
examined  with  negative  results. 

"That  infection  with  Habronema  musce  is  acquired 
during  some  stage  prior  to  the  imago  was  proved  by 
the  discovery  of  the  parasites  in  a  fly  caught  just  as  it 
was  emerging  from  the  pupa  (No.  9,  referred  to 
above).  Beyond  this  fact  the  observations  made  by 
me  (made  incidentally  in  the  course  of  another  in- 
vestigation) have  proved  little  as  to  the  life  history  of 
the  parasite.  On  several  occasions  I  have  placed  the 
worms  taken  from  flies  in  water  and  in  horse  manure, 
but  in  no  case  was  it  observed  that  any  further  develop- 
ment occurred.  The  worms  invariably  died  within  a 
few  days.  It  would  seem,  however,  that  the  larval 
stage  of  the  parasite  which  is  found  in  the  fly  must  in 
some  way  escape  from  its  host,  reach  sexual  maturity 
either  as  a  free  living  form  or  in  another  host,  and 
produce  young  which  find  their  way  into  other  flies 


NATURAL  ENEMIES  75 

during  an  early  stage  in  the  development  of  the  insects. 
It  is  improbable  that  the  worms  develop  to  maturity 
in  the  fly,  since  they  have  been  found  only  in  the  larval 
stage  in  that  host.  It  might  be  noted  in  this  connec- 
tion that  Carter  erred  in  identifying  certain  structures 
as  reproductive  organs." 

Other  nematodes  have  been  found  in  the  typhoid 
fly,  but  it  is  not  as  yet  determined  that  they  are  surely 
distinct  from  the  one  just  mentioned. 

THE  MITE  ENEMIES  OF  MUSCA  DOMESTICA 

Many  flies  of  different  species  are  often  noticed  to 
have  small  red  mites  attached  to  their  bodies.  This 
has  been  found  to  be  the  case  with  small  flies  as  well 
as  with  large  ones — even  mosquitoes  have  enemies  of 
this  kind.  Some  of  these  mites  probably  exert  a  dele- 
terious effect  upon  their  host  and  are  true  parasites, 
but  with  others  the  flies  simply  act  as  aeroplanes  to 
carry  the  mites  from  one  place  to  another.  (A  free  ride 
seems  to  be  the  only  object  for  which  they  have  at- 
tached themselves  to  the  fly.) 

Attention  was  called  to  these  mites  in  the  first  place 
by  DeGeer  in  1735.  Linnaeus  wrote  of  one  of  them  in 
1758,  and  other  writers  have  made  mention  of  them 
and  have  described  several  species.  Mr.  Nathan  Banks, 
an  authority  upon  this  group  of  creatures  (Arachnids), 
has  given  the  writer  the  following  information : 

"Latreille  based  a  new  genus  and  species  on  mites 
from  the  house  fly,  and  he  called  it  Atomus  parasiticum. 
This  is  the  young  of  one  of  the  harvest  mites  of  the 


76    THE  HOUSE  FLY— DISEASE  CARRIER 

family  Trombidiidae,  but  the  adult  has  not  been  reared 
and  is  still  unrecognized  in  Europe.  Riley  found  these 
harvest  mites  on  house  flies  in  Missouri,  in  some  years 
so  abundantly,  he  says,  that  scarcely  a  fly  could  be 
caught  that  was  not  infested  with  some  of  them  cling- 
ing tenaciously  at  the  base  of  the  wings.  Later  he  suc- 
ceeded in  rearing  the  adult,  and  described  it  as  Trom- 
bidium  muscarum.  In  recent  years  Oudemans  has  de- 
scribed TrombidiuiJi  inusca  from  larval  mites  found 
on  house  flies  in  Holland. 

"All  these  forms  are  minute,  six-legged,  red  mites, 
which  cling  to  the  body  of  the  fly  and  with  their  thread- 
like mandibles  suck  up  the  juices  of  the  host.  They  are 
nearly  related  to  the  so-called  'red-bugs,'  or  'chig- 
gers,'  of  the  Southern  United  States.  When  ready  to 
transform,  they  leave  the  fly  and  cast  their  skins,  the 
mature  mite  being  a  free-living,  hairy,  scarlet  creature 
about  one  and  five-tenths  mm.  long.  The  adults  are 
usually  found  in  the  spring  and  early  summer,  while 
the  larvae  are  usually  found  in  the  autumn  on  house 
flies  and  other  insects. 

Mites  of  the  genus  Pigmeophorus,  of  the  family 
Tarsonemidae,  have  also  been  taken  on  house  flies. 
They  cling  to  the  abdomen  of  the  fly,  but  it  is  not  cer- 
tain whether  they  feed  on  the  insect  or  use  it  simply 
as  a  means  of  transportation.  The  hypopus,  or  mi- 
gratorial  nymphal  stage  of  several  species  of  Tyro- 
glyphus,  has  been  found  on  house  flies.  This  hypopus 
attaches  itself  by  means  of  suckers  to  the  body  of  any 
insect  that  may  be  convenient.  The  mites  do  not  feed 


NATURAL  ENEMIES  77 

on  the  fly,  but  when  the  fly  reaches  a  place  similar  to 
that  inhabited  by  the  mites  the  latter  drop  off,  cast 
their  skins,  and  start  new  colonies.  DeGeer  observed 
large  numbers  of  these  tiny  mites  on  the  back  and  neck 
of  the  house  fly.  Linnaeus  named  one  of  them  Acarns 
miiscarum.  Berlese  has  reared  from  stable  flies  what 
he  considers  as  this  Acarus  miiscaruni  of  Linnaeus,  and 
finds  that  the  adult  belongs  to  the  genus  Histiostoma. 

The  hypopi  most  commonly  found  on  the  house  fly  are 
those  of  the  common  household  cheese-  ham-  and  flour- 
mites.  All  through  the  summer  months,  and  in  warm 
houses  during  the  winter  months,  these  creatures  breed 
with  astonishing  rapidity  and  fecundity.  The  females 
bring  forth  their  young  alive,  and  these  in  turn  reach 
full  growth  and  reproduce  until  a  cheese,  once  infested 
by  a  few,  swarms  with  the  crawling  multitude  which 
causes  its  solid  mass  to  crumble  and  become  mixed  with 
excremental  pellets  and  cast-off  skins. 

During  the  summer  months  the  mites  are  soft-bodied 
and  have  comparatively  feeble  powers  of  locomotion, 
and,  as  they  become  numerous  enough  to  devour 
the  whole  of  a  cheese  with  no  other  food  at  hand,  it 
was  for  a  long  time  a  puzzle  to  know  what  became  of 
them  and  to  understand  how  a  cheese  could  become  in- 
fested without  coming  in  contact  with  another  infested 
cheese  or  without  being  placed  in  an  infested  room.  It 
has  been  learned,  however,  that  when  necessity  requires 
it  and  when  the  insects  happen  to  be  in  the  proper  stage 
of  growth,  they  have  the  power  not  only  of  almost  in- 
definitely prolonging  existence  but  of  undergoing  a 


78    THE  HOUSE  FLY— DISEASE  CARRIER 

complete  change  of  form,  acquiring  hard,  brown,  pro- 
tective coverings  into  which  all  of  the  legs  can  be  drawn 
in  repose.  In  this  hard  shell,  or  hypopus  state,  it  may 
remain  for  many  months  without  food. 

In  the  majority  of  cases,  however,  where  a  given 
cheese  is  completely  destroyed,  all  of  the  young  and 
old  mites  perish,  and  only  those  of  middle  age,  which 
are  ready  to  take  on  the  hypopus  condition,  survive. 
These  fortunate  survivors,  possessing  their  souls  in 
patience,  retire  into  their  shells  and  fast  and  wait,  and, 
as  everything  comes  to  him  who  waits,  some  lucky  day 
a  house  fly  comes  that  way  and  the  little  mite  clings 
to  it  and  is  carried  away  to  some  spot  where  another 
cheese  or  food  in  some  other  form  is  at  hand. 

SPIDERS  AS  FLY  ENEMIES 

In  spite  of  the  well-remembered  poem  beginning 
"'Will  you  walk  into  my  parlor?'  said  the  spider  to 
the  fly,"  it  is  a  curious  psychological  fact  that  the  writer 
had  practically  completed  the  writing  of  this  chapter 
on  the  natural  enemies  of  the  house  fly  before  he  dis- 
covered that  he  had  forgotten  to  say  anything  about 
spiders.  That  was  not  because  he  is  getting  old  and 
forgetful,  but  because  in  the  rooms  which  he  has  had 
the  good  fortune  habitually  to  frequent  during  later 
years  he  has  rarely  seen  a  spider.  Although,  if  given 
the  opportunity,  they  would  kill  an  unlimited  number 
of  flies,  they  are  not  permitted  to  build  their  webs  and 
increase  in  localities  where  the  flies  are  the  greatest 
nuisances;  that  is  to  say,  in  houses,  shops,  and  hos- 


NATURAL  ENEMIES  79 

pitals.  It  will  not  be  necessary,  therefore,  to  give, 
spiders  any  extended  consideration  here.  Mr.  Nathan 
Banks,  the  well-known  writer  on  these  interesting  crea- 
tures, has  jotted  down  for  the  writer  the  following 
brief  notes  on  the  subject : 

"The  most  common  spider  in  houses  is  Theridium 
tepidariorum  Koch.  It  occurs  throughout  the  civilized 
world.  It  builds  an  irregular  web  in  the  upper  corners 
of  rooms,  and  if  the  housewife  is  not  too  tidy,  one  may 
often  see  flies  in  its  webs.  Steatoda  borealis  and  Teutana 
triangulosa  are  related  spiders,  occurring  in  this  coun- 
try and  in  Europe;  their  webs  are  commonly  under  or 
behind  furniture,  in  darker  places  than  those  of  the 
Theridium.  They  do  not  catch  as  many  flies,  but  their 
webs  are  safer  from  the  housekeeper's  broom. 

"Agalena  ncevia,  a  common  field  spider,  is  frequently 
found  in  houses,  especially  outhouses,  outside  kitchens, 
etc. ;  sometimes  they  live  in  these  double  screens ;  they 
need  some  crack  or  hole  in  which  to  retire;  the  web 
spreading  fan-like  from  this  hole,  which  they  line  with 
silk. 

"Salticus  scenicus  is  a  common  jumping  spider  about 
houses,  usually  on  the  outer  side  of  houses,  but  often 
seen  on  windows,  where  one  may  watch  with  much  in- 
terest their  method  of  stalking  and  suddenly  leaping 
on  unsuspecting  flies. 

"In  cellars,  packing  boxes,  and  other  dark  places, 
other  spiders  occur;  Tegenaria  derhami  and  Amauro- 
bius  ferox  being  common  in  the  United  States  and  in 
Europe. 


80    THE  HOUSE  FLY— DISEASE  CARRIER 

"Several  of  the  orb-weaving  spiders  are  often  found 
on  porches,  where  their  snares  will  intercept  many 
flies.  Epcira  scricata  nearly  always  occurs  near  or  on 
buildings." 

FALSE  SCORPIONS  ON  FLIES 
^ 

There  is  a  group  of  Arachnids,  known  as  the  false 
scorpions  or  pseudoscorpions,  which  are  much  smaller 
and  simpler  in  structure  than  the  true  scorpions.  They 
have  no  poison  gland  and  no  spine  at  the  end  of  the 
body.  They  bear  much  the  same  relation  to  the  true 
scorpions  that  the  mites  do  to  the  true  spiders.  They  live 
beneath  the  bark  of  trees,  in  moss,  between  the  leaves 
of  old  books,  etc.  They  run  sidewise  and  backwards, 
and  live  on  mites  and  small  insects.  Two  or  three 
species  of  the  false  scorpions  are  sometimes  found 
clinging  by  their  claw-like  pedipalps  to  the  legs  of  the 
house  fly  and  other  kinds  of  flies.  It  is  not  known 
why  they  attach  themselves  to  these  insects,  but  it  is 
hardly  probable  that  they  feed  on  them,  and  it  seems 
altogether  likely  that  they  simply  attach  themselves  in 
the  same  way  as  does  the  hypopus  of  the  Tyroglyphid 
mite,  in  order  to  be  carried  to  some  better  feeding 
ground.  Much  has  been  written  upon  this  subject, 
and  many  different  views  are  held  about  this  attach- 
ment, but  there  is  no  sound  evidence  on  the  one  side 
or  on  the  other.  The  suggestion  has  been  made  that 
the  false  scorpion  seizes  the  legs  of  the  flies  without 
realizing  their  size,  and  that  they  remain  attached  until 
the  fly  dies  and  then  they  feed  upon  the  body.  Doctor 


NATURAL  ENEMIES  81 

Hewitt  has  reviewed  the  habits  of  one  of  the  species 
known  as  Chernes  nodosus  Schrank,  which,  he  states, 
is  more  abundant  in  England  in  some  years  than  in 
others.  He  quotes  Godfrey  (1909):  "The  ordinary 
habitat  of  Chernes  nodosus,  as  Mr.  Wallace  Kew  has 
pointed  out  to  me,  appears  to  be  among  refuse,  that  is, 
accumulations  of  decaying  vegetation,  manure  heaps, 
frames  and  hotbeds  in  gardens.  He  refers  to  its  occur- 
rence in  a  manure  heap  in  the  open  air  at  Lille,  and 
draws  my  attention  to  its  abundance  in  a  melon  frame 
near  Hastings  in  1898,  where  it  was  found  by  Mr. 
W.  R.  Butterfield."  Doctor  Hewitt  very  justly  calls 
attention  to  the  fact  that  it  is  not  difficult  to  under- 
stand the  frequent  occurrence  of  this  false  scorpion 
on  the  legs  of  flies,  in  view  of  the  facts  just  quoted 
from  Mr.  Godfrey,  since  flies  frequent  such  rubbish 
heaps  for  the  purpose  of  laying  eggs,  or  he  suggests 
that  when  they  have  recently  emerged  from  puparia 
in  such  places  and  are  crawling  about  while  their  wings 
are  drying  their  legs  are  readily  to  be  seized  by  the 
Chernes.  In  closing  his  account  of  this  species  he 
writes,  "It  is  obvious  that  the  association  [between 
the  Chernes  and  the  fly]  will  result  in  the  distribution 
of  the  pseudoscorpionid,  but  whether  this  is  merely 
incidental  and  the  real  meaning  lies  in  a  parasitic  or 
predaceous  intention  on  the  part  of  the  Arachnid,  as 
some  of  the  observations  appear  to  indicate,  further 
experiments  alone  will  show." 


82    THE  HOUSE  FLY— DISEASE  CARRIER 

THE  HOUSE  CENTIPEDE 

There  is  a  small,  rather  fragile-looking  centipede, 
known  scientifically  as  Scutigcra  forceps  Raf.,  which 
for  many  years  has  been  a  constant  inhabitant  of  houses 
in  the  Southern  United  States,  and  which  seems  to 
have  been  gradually  extending  its  northward  range. 
It  is  now  occasionally  found  in  houses  as  far  north 
as  Albany.  N.  Y.,  and  perhaps  even  farther. 

It  seems  to  be  peculiarly  a  domestic  animal ;  that  is 
to  say,  it  has  accommodated  itself  perfectly  to  the  con- 
ditions existing  in  human  habitations.  Its  form  and 
its  sudden  movements  have  made  it  an  object  of  fear, 
especially  to  women  and  children.  It  is  fond  of  damp 
localities,  and  is  especially  abundant  in  bathrooms,  in 
basements,  in  cellars,  and  in  ground-floor  kitchens  and 
pantries,  where  there  is  more  or  less  dampness  and 
warmth.  It  has  been  called  the  skein  centipede,  since 
when  crushed  its  long  legs  look  like  a  mass  of  threads. 
This  creature,  as  has  been  shown  by  Marlatt  (1896), 
seems  to  be  a  normal  inhabitant  of  the  southern  tier 
of  the  United  States,  spreading  north  into  Pennsyl- 
vania as  early  as  1849  and  reaching  New  York  and 
Massachusetts  twenty  or  twenty-five  years  later.  It 
is  now  common  throughout  New  York  and  the  New 
England  States  and  extends  westward  beyond  the 
Mississippi. 

The  character  of  its  mouth  parts  indicates  that  it  is 
predatory  and  carnivorous  in  its  habits;  the  jaws  are 
strong,  and  its  food  consists  principally  of  other  in- 


Fig.  17.— The  house  centipede  (Scutigera  forceps)  ;  somewhat  enlarged. 
(After  Marlatt.) 


NATURAL  ENEMIES  83 

sects  living  in  houses,  such  as  house  flies,  small  cock- 
roaches, and  clothes  moths.  Years  ago  the  writer  ob- 
served its  method  of  catching  both  Croton  bugs  and 
house  flies  upon  the  wall  of  the  kitchen  of  a  house  in 
which  he  lived  in  Georgetown,  D.  C.  It  feeds  and  is 
especially  active  at  night,  being  seen  in  the  daytime 
usually  only  when  disturbed.  On  this  occasion,  with 
the  late  Dr.  James  Fletcher,  the  writer  went  to  the 
pantry  in  the  evening  and  saw  a  good-sized  specimen 
of  the  Scutigera  on  the  wall  eating  something.  The 
light  was  turned  as  low  as  was  consistent  with  fairly 
clear  observation.  The  object  held  in  its  front  legs 
was  seen  to  be  a  small  Croton  bug.  It  was  eaten  with 
astonishing  rapidity,  but  in  the  act  of  eating  this  speci- 
men a  house  fly  was  observed  by  the  centipede,  close 
to  it,  resting  upon  the  wall.  It  instantly  jumped,  ap- 
parently with  all  of  its  legs  at  once,  and  covered  the 
fly,  which  was  thus  confined  as  if  it  had  been  in  a  hen 
coop.  When  the  Croton  bug  was  devoured,  the  pair 
of  legs  opposite  the  fly  seized  it  and  passed  it  to  the 
pair  of  legs  immediately  in  front,  and  in  succession 
it  was  passed  up  to  the  front  legs,  by  which  it  was  held 
while  being  devoured.  So  it  is  obvious  that  its  great 
number  of  legs  are  of  use,  not  only  in  walking,  but 
in  the  capture  of  its  prey.  The  same  operation  was 
repeated  several  times. 

The  popular  belief  is  that  this  little  creature  is  very 
poisonous,  and  indeed  it  belongs  to  the  poisonous  group 
of  centipedes.  Very  few  cases  are  recorded,  however, 
of  its  having  bitten  a  human  being,  and  it  is  question- 


84    THE  HOUSE  FLY— DISEASE  CARRIER 

able  whether  it  would  attack  any  animal  or  insect  larger 
than  itself.  Marlatt  states  that  if  pressed  with  the 
bare  foot  or  hand,  or  if  caught  between  sheets  in  beds, 
it  will  unquestionably  bite  in  self-defense.  He  also 
shows  that  the  few  such  cases  on  record  indicate  that 
severe  swelling  and  pain  may  result  from  the  poisonous 
injection.  Prompt  application  of  ammonia,  however, 
will  alleviate  the  symptoms. 

No  one  knows  much  about  the  life  history  of  this 
creature.  Full-grown  specimens  are  found  in  houses 
all  through  the  year;  half-grown  individuals  are  some- 
times found  in  the  summer;  the  youngest  ones  known 
differ  from  the  older  ones  chiefly  in  having  fewer  legs. 
It  is  interesting  to  note  that  a  careful  look  at  the  hind 
segments  of  the  young  will  show  the  long  posterior 
legs  folded  up  within  and  ready  to  be  extended  after 
the  next  molt. 

Under  present  conditions  of  house  fly  abundance,  it 
might  be  as  well  not  to  disturb  this  Scutigera  when 
it  is  found  in  houses,  but  with  the  conditions  which 
will  shortly  be  brought  about,  we  hope,  it  will  be  easy 
to  destroy  the  centipedes  with  pyrethrum  powder,  even 
if  they  do  not,  as  is  likely,  die  of  starvation. 

INSECT  ENEMIES  OF  THE  HOUSE  FLY 

Predatory  enemies. — It  seems  rather  strange  that, 
with  the  very  numerous  predaceous  insects  which  de- 
rive their  sustenance  from  soft-bodied  and  more  or  less 
helpless  species,  there  should  not  be  more  which  gain 
their  livelihood  from  the  larvae  of  the  typhoid  fly.  It 


NATURAL  ENEMIES  85 

is  true  that  the  larvae  of  certain  Carabaeid  beetles,  and 
especially  those  of  the  genera  Harpalus,  Platynus  and 
Agonoderus,  are  sometimes  found  frequenting  manure 
and  feeding  upon  young  fly  larvae,  and  that  certain 
rove  beetles  and  their  larvae,  of  the  family  Staphylinidae, 
are  also  found  in  the  same  situations,  engaged  in  the 
same  task.  And  Packard  (1874)  records  the  rinding 
of  a  beetle  pupa  in  the  puparium  of  the  house  fly.  But 
one  would  think  that  a  pile  of  horse  manure  swarming 
with  fly  larvae  would  attract  hordes  of  predatory  beetles 
and  of  pirate  bugs  and  the  like.  Is  it  that  house  fly 
maggots  are  distasteful  to  these  Voracious  creatures? 
Or  is  their  perception  of  odors  keen  and  are  the  am- 
moniacal  odors  of  the  manure  pile  repugnant?  It  is 
difficult  to  say.  The  typhoid  fly  belongs  plainly  to  a 
most  persistent  type,  and  it  feeds  freely  and  abundantly 
in  close  proximity  to  many  insects  which  we  would 
naturally  suppose  to  be  its  enemies. 

But  we  must  not  forget  the  ants.  It  is  true  that 
many  ants  are  nuisances,  and  in  the  case  of  the  destruc- 
tion of  the  typhoid  fly  by  ants  we  have  simply  one  nui- 
sance multiplying  at  the  expense  of  another,  but  Forel 
and  Wheeler  admit  that  as  a  group  ants  are  beneficial 
and  that  many  species  deserve  our  protection.  Capt. 
P.  L.  Jones  of  the  U.  S.  Army  Medical  Corps  (quoted 
by  Garrison,  U.  S.  Naval  Med.  Bull.,  Oct.,  1910,  p. 
551)  made  certain  experiments  in  the  Philippines  to 
determine  whether  the  scarcity  of  flies  in  those  islands 
was  due  to  some  epidemic  disease.  In  the  course  of 
the  experiments  it  was  found  impossible  to  raise  flies 


86    THE  HOUSE  FLY— DISEASE  CARRIER 

unless  the  eggs  and  larvae  (in  manure)  were  protected 
from  ants,  as  the  latter  invariably  carried  off  both 
eggs  and  larvae  and  even  pupae. 

In  the  work  against  the  cotton  boll  weevil  carried 
on  in  the  Southern  United  States  by  the  experts  of 
the  Bureau  of  Entomology  of  the  U.  S.  Department 
of  Agriculture,  it  was  found  that  the  "fire  ant"  of  the 
Southern  cotton  fields  (Solenopsis  gemminata,  var. 
diabola)  is  an  important  enemy  of  the  weevil,  and 
strong  efforts  were  made  to  multiply  the  ants.  It  was 
soon  found  that  they  were  strongly  attracted  to  horse 
manure  and  undoubtedly  destroyed  all  its  other  insect 
inhabitants.  Mr.  W.  D.  Pierce  of  the  Bureau  informs 
the  writer  that  the  little  black  ant  Monomorium  mini- 
mum also  frequents  horse  manure  heaps  in  Texas,  and 
he  also  says  that  several  species  of  the  ant  genus  Phei- 
dole  have  this  habit. 

Moreover,  that  famous  pest  in  Louisiana  and  parts 
of  California,  known  as  the  "Argentine  ant"  (Iri- 
domyrmex  humulis)  nests  readily  dn  horse  manure,  and 
its  active,  pugnacious  and  predatory  habits  undoubtedly 
induce  it  to  prey  upon  the  maggots  found  there. 

Mr.  Pierce' s  ant  suggestion  was  of  sufficient  interest 
to  follow  up,  and  therefore  the  writer  has  corresponded 
with  Prof.  Wilmon  Newell,  of  College  Station,  Texas ; 
Prof.  J.  B.  Garrett  of  the  State  University  of  Louisiana 
at  Baton  Rouge;  and  Mr.  T.  C.  Barber,  in  charge  of 
the  Audubon  Park  laboratory  of  the  U.  S.  Bureau  of 
Entomology  at  New  Orleans — all  of  them  men  who 
have  had  intimate  acquaintance  with  the  Argentine  ant, 


NATURAL  ENEMIES  87 

and  who  have  made  special  studies  of  its  habits.     The 
reply  from  each  was  the  same  in  its  general  tone. 

Professor  Newell  never  found  the  Argentine  ant 
nesting  in  pure  horse  manure,  but  has  found  them  in 
manure  that  contained  a  large  amount  of  straw  or  hay. 
A  certain  public  dumping  ground  carrying  much  ma- 
nure was  heavily  infested  with  the  ants,  but  house  flies 
bred  from  it  in  such  enormous  numbers  that  the  health 
officer  was  called  in.  The  observer  found  colonies  of 
ants  on  the  ground  and  also  an  abundance  of  fly  larvae. 
His  experience  has  been  that  house  flies  are  not  notice- 
ably reduced  in  places  where  the  Argentine  ant  swarms. 

Professor  Garrett  writes  that  the  mess  hall  in  which 
about  300  of  the  students  take  their  meals  is  in  a  lo- 
cality where  the  ants  are  very  abundant,  and  yet  the 
house  flies  are  apparently  as  numerous  as  ever.  He 
thinks  that  the  ants  do  destroy  quite  a  number  of  lar- 
vae in  manure,  but  that  they  do  not  use  them  as  an 
article  of  food  to  a  sufficient  extent  to  cause  an  appre- 
ciable decrease.  Mr.  Barber  is  of  the  same  opinion. 

Mr.  F.  C.  Pratt,  an  agent  of  the  Bureau  of  Entomol- 
ogy, located  at  Sabinal,  Texas,  made  an  especial  study 
of  fly  larvae  at  Dallas  on  one  occasion.  He  found  that 
the  fire  ant,  on  one  occasion  when  he  was  experiment- 
ing with  cow  manure  in  order  to  raise  parasites  of  the 
horn  fly,  took  complete  possession  of  his  rearing  cages 
and  their  contents.  In  his  opinion,  they  feed  upon  all 
fly  larvae. 

Aside  from  ants,  there  are  other  predatory  insect  ene- 
mies of  flies  not  yet  mentioned.  Wasps  catch  house 


88    THE  HOUSE  FLY— DISEASE  CARRIER 

flies,  sometimes  in  considerable  numbers.  It  is  not  an 
uncommon  sight  to  see  any  one  of  several  different 
species  of  wasps  flying  about  houses,  capturing  flies 
both  on  the  wall  and  on  .the  wing.  The  robber  flies  of 
the  family  Asilidae  also  catch  house  flies,  on  porches 
sometimes.  On  the  whole,  however,  the  predatory  in- 
sect enemies  of  the  house  fly  are  negligible,  so  far  as 
the  beneficial  result  of  their  work  is  concerned. 

Parasitic  Enemies 

To  a  certain  extent  the  same  may  be  said  of  the  para- 
sitic enemies  of  this  species,  but  these  are  perhaps  more 
numerous  than  the  predatory  insect  enemies,  and  sev- 
eral of  them  are  accustomed  to  frequent  excreta  in  the 
search  of  larvae  in  which  to  deposit  their  eggs.  This 
is  especially  true  of  cow  dung,  and  many  minute  hy- 
menopterous  parasites  may  be  found  frequenting  drop- 
pings in  the  pasture  in  order  to  lay  their  eggs  in  some 
one  of  the  many  species  of  maggots  which  are  to  be 
found  there  in  a  very  short  time. 

These  very  minute,  active,  four-winged  parasites  be- 
long either  to  the  subfamily  Figitinse  of  the  gall-fly 
family  Cynipidse  or  to  the  superfamily  of  true  parasites 
known  as  Chalcidoidea. 

In  the  gall-fly  family,  Cynipida?,  most  of  the  species 
of  which  produce  galls  upon  living  plants  and  very 
numerously  upon  the  oak,  there  is  one  subfamily  of 
minute  forms,  the  Figitinse,  parasitic  upon  other  insects 
and  for  the  most  part  upon  dipterous  maggots.  Those 
frequenting  cow  dung  will  lay  their  eggs  in  apparently 


NATURAL  ENEMIES  89 

almost  any  one  of  the  many  species  of  dipterous  larvae 
found  there,  and  have  been  reared  from  the  larvae  of 
the  horn  fly,  from  several  species  of  true  dung-flies 
(family  Scatophagidae),  and  from  others.  Two  spe- 
cies, however,  are  reared  from  the  maggots  of  the  ty- 
phoid fly.  These  are  Figites  anthotnyiarum,  reared 
from  the  house  fly  in  Germany  by  Reinhard,  and 
Figites  scutellaris,  also  a  European  species.  If  careful 
rearing  experiments  were  carried  out  continuously  in 
this  country  with  house  fly  larvae,  it  is  probable  that 
other  species  of  this  group  would  be  reared.  Prof. 
T.  D.  A.  Cockerell,  for  example,  caught  one  of  them — 
Eucoila  impatiens  Say — on  horse  dung  at  Las  Cruces, 
N.  Mex.,  in  1894,  and  suspected  its  parasitism  on  house 
fly  larvae  (Insect  Life,  VII,  209).  Many  similar  ob- 
servations can  doubtless  be  made  very  easily. 

The  Chalcidoid  parasites  of  Musca  domestica  are 
more  numerous.  In  the  family  Pteromalidae  there  is 
a  genus,  Spalangia,  which  seems  practically  confined  to 
dipterous  larvae.  One  species,  Spalangia  niger,  was 
found  by  the  German  author  Bouche  to  lay  its  eggs  in 
the  pupae  of  the  house  fly  and  to  issue  in  April  and 
May.  The  larvae  of  the  Spalangia  are  spindle-formed 
and  white,  almost  translucent,  and  are  to  be  found  in 
the  autumn  in  the  puparia  of  the  house  fly,  where  they 
destroy  the  true  pupae. 

Several  species  belonging  to  this  same  genus  are  to 
be  found  in  the  United  States,  and  one  of  them  at  least 
has  similar  habits.  Mr.  H.  L.  Sanford,  of  the  Bureau 
of  Entomology  at  Washington,  in  opening  a  series  of 


90    THE  HOUSE  FLY— DISEASE  CARRIER 

puparia  of  Musca  domestica  in  January,  1911,  in  order 
to  ascertain  what  proportion  of  the  pupae  were  living, 
was  surprised  when  a  fully  formed  and  active  adult 
black  Spalangia  crawled  immediately  from  the  opening 
made  by  his  dissecting  needle.  This  will  be  described 
by  Girault  as  Spalangia  musccc.  A  certain  proportion 
of  the  house  fly  puparia  are  affected  by  this  parasite  in 
precisely  the  same  way  as  are  the  puparia  in  Europe 
by  Spalangia  nigcr  as  described  by  Bouche.  Mr.  San- 
ford's  observation  shows  that  the  adults  may  be  fully 
formed  and  ready  to  emerge  at  a  very  early  date. 

Another  European  Pteromalid  parasite,  namely,  Ste- 
nomalus  mnscarum,  is  recorded  as  being  a  parasite  of 
the  house  fly  pupa. 

Much  attention  has  been  given  to  the  Chalcidoid 
parasites  of  the  typhoid  fly  by  A.  A.  Girault  and  G.  E. 
Sanders,  of  the  University  of  Illinois.  In  their  first 
paper  (Psyche,  December,  1909,  pp.  119-132)  they 
described  an  interesting  form  under  the  name  Nasonia 
brcvicornis  from  a  series  of  640  specimens,  nearly  all 
reared  from  puparia  of  various  flies  in  the  Office  of  the 
State  Entomologist  of  Illinois  at  Urbana  during  1908. 
They  came  from  various  decomposing  materials,  from 
which  several  species  of  flies  were  reared,  but  a  num- 
ber undoubtedly  came  from  Musca  domestica. 

It  is  a  minute,  dark,  metallic,  brassy-green  fly  with 
clear  wings  and  rather  stolid  and  serious  temperament. 
Girault  and  Sanders  state  that  it  heeds  external  influ- 
ences very  slightly,  and  quietly  and  persistently  gives 
its  whole  attention  to  reproduction.  They  found  that 


NATURAL  ENEMIES  91 

both  sexes  crawled  rapidly.  The  female  is  able  to  fly ; 
but  the  favorite  mode  of  locomotion  appears  to  be 
crawling.  The  wings  of  the  male  appear  to  be  non- 
functional. Actual  experimentation  with  fifty  maggots 
and  ten  puparia  of  the  house  fly  showed  that  the  para- 
sites laid  their  eggs  in  the  puparia  and, developed  rap- 
idly. The  maggots  and  puparia  were  placed  in  a  breed- 
ing jar  on  September  pth,  and  on  September  26th  six 
males  and  ten  females  of  the  parasites  issued  from  the 
puparia.  On  September  I2th,  eight  female  parasites 
were  confined  separately  in  small  gelatine  capsules, 
each  with  a  healthy  puparium  of  the  house  fly.  The 
parasites  appeared  to  lay  their  eggs  in  several  cases, 
but  none  issued  afterwards  and  about  half  of  the  flies 
came  out. 

Most  careful  observations  were  made  by  the  authors 
on  the  egg-laying  process  of  this  parasite.  The  female 
was  observed  to  walk  carefully  over  a  two-days'  old 
puparium,  examining  the  entire  surface.  After  a  point 
was  selected,  the  ovipositor  was  inserted  with  some  dif- 
ficulty, the  operation  requiring  one  minute  and  a  half. 
The  hole  was  then  enlarged,  and  the  ovipositor  was 
again  pushed  in  for  its  entire  length  and  remained  for 
forty-five  seconds,  during  which  time  apparently  an 
egg  was  deposited.  After  the  ovipositor  was  with- 
drawn the  parasite  examined  the  puncture  with  its 
antennse  and  mandibles. 

The  parasite  apparently  attacks  only  the  puparium, 
and  that  only  after  it  has  been  formed  for  about  twenty- 
four  hours,  and  a  number  of  them  issue  from  the  same 


92    THE  HOUSE  FLY— DISEASE  CARRIER 

puparium.  Observations  were  carried  on  through  suc- 
ceeding months  and  the  duration  of  the  life  cycle  was 
carefully  studied  (Psyche,  February,  1910).  The  life 
cycle  is  longer  in  the  spring  and  shorter  in  summer, 
the  average  life  cycle  being  twenty-two  and  one- 
half  days  with  usual  temperature.  They  found  that 
one  female  was  able  to  parasitize  twenty-two  puparia 
and  another  one  seventeen.  The  authors  suspect  that 
the  phenomenon  of  polyembryony,  that  is  to  say,  the 
development  of  a  number  of  adult  individuals  from  a 
single  egg,  takes  place  with  this  species.  Counts  of 
several  thousand  reared  specimens  of  the  parasite  in- 
dicated that  fifty-eight  and  nineteen-hundredths  per 
cent,  of  them  were  female  and  forty-one  and  eighty-one- 
hundredths  per  cent,  were  males.  They  found  that  the 
adult  parasites  issue  from  the  host  puparium  through 
from  one  to  three  circular  holes  of  various  positions, 
several  issuing  from  each  hole.  As  to  the  abundance 
of  the  parasite,  the  authors  indicate  that  during  Sep- 
tember and  October,  1908,  they  reared  8,000  or  more 
specimens,  and  these  were  reared  quite  accidentally,  that 
is  to  say,  without  conscious  effort  on  their  part  to  in- 
crease the  number.  The  local  abundance  of  the  para- 
site was  indicated  by  the  fact  that  in  a  portion  of  a 
given  experiment  the  percentage  of  parasitism  was  as 
high  as  ninety  per  cent.  This  percentage  of  mortality 
on  the  part  of  the  house  fly,  however,  was  by  no  means 
general,  and  the  parasite  had  apparently  concentrated 
its  attack  on  certain  spots.  The  authors  made  an  un- 
successful attempt  to  propagate  the  species  artificially 


NATURAL  ENEMIES  93 

by  scattering  1,000  specimens  of  mixed  sexes  over  a 
garbage  heap  on  September  23d.  This,  however,  was 
too  late  in  the  season,  and  weekly  collections  of  fly 
puparia  thereafter  gave  no  result. 

The  authors  found  that  this  parasite  hibernates  as 
a  full-grown  larva  in  the  puparia  of  the  flies,  trans- 
forming to  pupa  early  in  the  spring  and  emerging 
shortly  afterwards.  As  examples  of  intensive  and  care- 
ful study  of  a  given  species,  the  papers  on  this  form  by 
the  authors  mentioned  are  excellent. 

The  same  authors  have  made  a  careful  study  of  an- 
other house  fly  parasite  of  this  group,  known  as  Pachy- 
crepoideus  dubius.  This  species  was  reared  in  com- 
pany with  the  preceding  species,  and  the  experiments 
of  the  writers  indicated  that  it  is  a  true  primary  para- 
site of  the  house  fly.  They  were  unable  to  make  any 
observations  on  the  biology  of  the  species,  except  to 
notice  that  the  adults  in  three  cases  emerged  from  the 
fly  puparium  through  a  single  hole  with  jagged  edges. 

Still  another  parasite  of  this  group,  studied  by  Gir- 
ault  and  Sanders,  and  described  in  Psyche  for  August, 
1910,  is  Muscidifurax  raptor.  This  is  another  small, 
clear-winged  species,  black  in  color,  which  was  reared 
in  some  numbers  from  puparia  of  the  typhoid  fly  at 
Urbana  and  Champaign,  Illinois.  It  also  breeds  in 
the  puparia  of  other  flies,  is  solitary  in  its  habits,  and 
more  sensitive  than  the  Nasonia  which  the  experiment- 
ers have  described  so  fully.  They  state  that  the  bio- 
logical history  of  the  species  can  be  learned  with  ease 
in  the  laboratory,  as  the  females  are  not  at  all  averse 


94    THE  HOUSE  FLY— DISEASE  CARRIER 

to  ovipositing  in  confinement ;  they  are,  however,  seem- 
ingly not  as  prolific  or  as  generally  parasitic  as  Nasonia. 

The  writers  did  not  obtain  certain  data  concerning 
the  entire  seasonal  history  of  this  parasite,  but  they 
think  that  it  confines  itself  principally  to  the  puparium 
stage  of  the  house  fly,  hibernating  in  the  puparium  as 
a  larva  and  pupating  itself  and  emerging  early  in  the 
spring  as  an  adult  four-winged  parasite.  The  first 
specimens  found  by  them  emerged  the  first  week  in 
September,  and  from  that  time  on  until  frost  it  was 
comparatively  abundant.  It  was  reared  from  puparia 
collected  on  September  23d  and  again  from  some  col- 
lected on  October  2ist,  emerging  from  these  Novem- 
ber 6th.  Hibernation  probably  commenced  about  Oc- 
tober 2 1  St. 

Examination  of  the  house  fly  pupae,  after  the  para- 
sites have  emerged,  indicates  that  the  larva  of  the  para- 
site feeds  externally  on  the  pupa  of  the  fly,  sucking  its 
juices.  The  attachment  is  to  any  portion  of  the  body 
of  the  pupa.  Opening  a  puparium  from  which  the 
adult  parasite  had  emerged  revealed  the  blackened  and 
shrunken  remains  of  the  fly  pupa  lying  in  its  natural 
position  along  the  floor  of  the  pupal  shell. 

The  meconium,  or  excrement  passed  by  the  para- 
site larva  when  about  to  change  to  pupa,  is  distinctive 
— dark  in  color  and  round-angled,  looking  like  a  small, 
solid,  black,  round  bit,  resembling  somewhat  a  coarse 
grain  of  powder  but  not  as  irregular  or  angular.  It 
differs  from  the  meconium  of  the  other  parasites  of  the 
house  fly  studied  by  the  authors  mentioned.  The  adult 


NATURAL  ENEMIES  95 

parasite  issues  through  a  single  rounded  hole  cut  in 
the  pupal  skin  of  the  fly.  The  two  sexes  issue  almost 
simultaneously,  the  males  a  little  before  the  females. 
Each  female  appears  to  lay  thirty  to  forty  eggs.  Out 
of  288  specimens  reared,  eighty-five  were  males  and 
203  females,  and  the  average  duration  of  the  life  cycle 
was  nineteen  days  and  seventeen  hours. 

Girault  will  continue  his  intensive  study  of  fly  para- 
sites and  will  undoubtedly  learn  many  new  and  im- 
portant facts.  Additional  species  have  already  been 
reared  by  him  and  await  systematic  study. 

VERTEBRATE  HOUSE  FLY  ENEMIES 

The  common  garden  toad,  the  great  collector  of  in- 
sects, will  catch  a  house  fly  whenever  it  is  able  to  do  so. 
It  is,  in  fact,  a  pleasing  occupation  to  feed  house  flies 
to  a  good-sized  toad,  in  order  to  ascertain  his  capacity. 
But  these  animals  are  not  inhabitants  of  houses. 

Some  of  the  lizards  that  run  about  houses  in  tropical 
regions  feed  upon  flies,  and  the  occupancy  of  houses 
by  these  creatures  is  not  objected  to  by  natives,  for  this 
as  well  as  for  other  reasons. 

Birds  are  not  effective  as  house  fly  enemies.  Of  the 
wild  birds,  comparatively  few  feed  upon  them  at  all, 
although  there  are  many  insectivorous  species  which 
would  do  so  if  they  were  allowed  to  nest  in  houses.  As 
a  matter  of  fact,  however,  in  all  the  records  of  the  Bu- 
reau of  Biological  Survey  of  the  U.  S.  Department  of 
Agriculture,  which  represent  the  examination  of  the 
contents  of  the  stomachs  of  many  thousands  of  birds, 


96    THE  HOUSE  FLY— DISEASE  CARRIER 

there  are  only  two  records  of  the  finding  of  house  flies, 
and  one  of  these  is  somewhat  doubtful. 

One  of  their  records  shows  the  finding  of  thirty-three 
larvae  in  the  stomach  of  a  horned  lark,  but  it  is  quite 
possible  that  these  larvae  were  not  those  of  Musca  do- 
mestica.  The  other  record  shows  the  finding  of  a  single 
adult  house  fly  in  the  stomach  of  a  white-eyed  vireo. 
The  writer  has  watched  the  house  wren  feeding  its 
young  hour  after  hour,  and  has  noticed  that  the  in- 
sects brought  to  the  nest  were  for  the  most  part  small 
caterpillars,  although  there  were  plenty  of  flies  on  the 
porch  where  the  nest  was  built. 

The  great  group  of  insectivorous  birds  known  as  the 
fly-catchers  as  a  matter  of  fact  do  not  prefer  the  flies. 
As  the  writer  has  been  told  by  Prof.  F.  E.  L.  Beal,  an 
authority  on  the  subject,  they  feed  by  preference  upon 
winged  hymenopterous  insects,  which  constitute  the 
bulk  of  their  food. 

W.  D.  Doan  in  Bulletin  3  of  the  West  Virginia  Ex- 
periment Station  records  finding  house  flies  in  the 
stomachs  of  the  cedar  bird,  the  wood  pewee,  and  the 
palm  warbler. 

Domestic  poultry,  however,  when  given  the  oppor- 
tunity, will  feed  with  some  avidity  upon  house  fly  lar- 
vae. Hens  given  the  run  of  a  barnyard  destroy  very 
many  larvae  in  scraping  about  the  edge  of  the  manure 
pile,  and  more  than  one  letter  has  been  received  from 
persons  who,  admitting  flocks  of  poultry  to  the  barn- 
yard for  the  first  time,  have  discovered  an  appreciable 
reduction  in  the  number  of  adult  flies  visiting  the  house. 


NATURAL  ENEMIES  97 

Fly-Catching  Rats 

A  number  of  mammalia  in  captivity  have  been  seen 
to  capture  flies,  but  as  a  rule  they  seem  to  do  this  very 
much  as  the  idle  house  dog  will  snap  at  the  fly  circling 
about  his  head.  A  most  interesting  observation,  how- 
ever, has  been  made  by  Prof.  B.  W.  Evermann,  of  the 
Bureau  of  Fisheries  in  Washington.  At  a  meeting  of 
the  Biological  Society  of  Washington,  held  January 
7th,  he  gave  an  account  of  a  visit  in  early  July  of  1910, 
at  Kokomo,  Indiana.  He  stopped  at  a  hotel  and  was 
sitting  on  the  piazza  on  the  evening  of  his  arrival.  Back 
of  him  was  a  window  which  opened  into  a  storeroom 
for  provisions,  etc.  Inside  the  window  was  a  lace  cur- 
tain which  hung  closely,  and  uniformly  covered  the 
entire  window.  Happening  to  look  at  the  window  quite 
by  accident,  Professor  Evermann  saw  a  brown  rat  run 
back  and  forth  on  the  window-sill  inside.  It  seems  that 
a  large  number  of  flies  had  accumulated  between  the 
curtain  and  the  window,  probably  attracted  by  the  light 
from  outside,  and  the  rat  was  engaged  in  catching  these 
flies. 

In  Professor  Evermann's  words,  "It  was  very  expert. 
It  would  move  back  and  forth  the  full  length  of  the 
window-sill,  catching  such  flies  as  it  could  reach.  It 
would  frequently  stand  upon  its  hind  legs  to  its  full 
length  with  its  fore  paws  and  body  resting  against  the 
glass  and  move  backward  and  forward  across  the  win- 
dow. It  ordinarily  caught  the  flies  with  its  paws,  by 
raking  the  fly  with  one  paw  over  against  the  other  or 


98    THE  HOUSE  FLY— DISEASE  CARRIER 

bringing  the  two  paws  together  on  a  fly  and  then  feed- 
ing it  into  its  mouth." 

The  observer  watched  it  for  some  little  time  and 
must  have  seen  it  catch  more  than  one  hundred  flies. 
Next  morning  the  same  performance  was  repeated,  and 
a  large  number  of  flies  were  captured.  Moreover,  a 
second  rat  appeared  during  the  time  the  observer  was 
watching  the  first  one,  and  its  methods  were  the  same. 
Inquiry  from  the  clerk  at  the  hotel  indicated  that  the 
people  of  the  hotel  had  noticed  the  rats  engaged  in  this 
occupation  and  had  refrained  from  disturbing  them. 

Mr.  W.  L.  McAtee,  recently,  in  looking  over  an  old 
file  of  The  Rod  and  the  Gun  found  the  following  item 
in  the  number  of  September  25,  1875.  It  is  quite  be- 
lievable in  view  of  Doctor  Evermann's  personal  ob- 
servations : 

"Mr.  C.  B.  Odell,  at  his  hotel  on  Front  Street,  is  the 
happy  owner  of  a  fly  exterminator,  which,  for  thor- 
ough work,  is  unsurpassed  by  anything  we  have  ever 
seen.  In  one  of  the  windows  facing  Front  Street, 
where  samples  of  his  wares  are  occasionally  shown,  a 
rat  began  several  weeks  since  to  make  sly  visits,  and 
secured  a  good  meal  as  often  as  he  came  by  catching 
the  many  flies  which  are  on  the  panes  of  glass.  He 
grew  very  expert  at  it,  and  though  at  first  quite  shy, 
soon  became  emboldened  when  he  found  he  was  not 
disturbed  in  his  foraging  expeditions,  and  would  pur- 
sue his  business  not  in  the  least  intimidated  by  spec- 
tators, who  were  only  separated  from  him  by  a  pane 
of  glass.  He  obtained  entrance  to  this  window  by 


NATURAL  ENEMIES  99 

gnawing  a  hole  through  the  wooden  base,  coming  from 
below.  For  weeks  he  has  pursued  his  fly-hunting  busi- 
ness undisturbed. 

"On  Sunday  one  of  the  waiters  discovered  him  in 
the  act  of  introducing  a  friend  or  member  of  his  family 
to  his  foraging  ground.  The  newcomer  was  very  shy, 
and  only  put  his  head  through,  while  the  old  habitue 
tried  to  coax  him  in  the  window.  He  would  catch  a 
fly,  gravely  hand  it  to  his  friend,  who  would  as  gravely 
eat  it,  and  look  for  more.  By  degrees  he  lost  a  little 
of  his  fear,  walked  out,  and  soon  became  an  expert  in 
the  new  business.  Either  one  or  both  may  be  seen  al- 
most any  day  by  any  one  who  may  be  patient  enough  to 
wait  for  their  appearance  a  short  time.  It  is  certainly 
a  very  novel  sight,  and  well  worth  a  few  minutes'  time 
to  see. — Neivburgh  Telegraph." 

Mr.  Nat.  C.  Dearborn,  of  the  Biological  Survey  of 
the  U.  S.  Department  of  Agriculture,  states  that  he  has 
frequently  seen  evidence  of  the  destruction  of  adult 
flies  by  mice  on  window-sills,  the  work  having  been 
done  at  night. 


Ill 

THE  CARRIAGE  OF  DISEASE  BY  FLIES 

IT  would  probably  be  impossible  to  trace  the  first  sug- 
gestion of  the  carriage  of  disease  by  flies.  They 
have  been  conspicuously  connected  with  accounts  of 
epidemics  of  one  kind  or  another  for  hundreds  of  years, 
and  before  discussing  some  of  the  specific  diseases 
which  they  are  thought  to  carry  some  attention  may  be 
given  to  some  of  these  early  suggestions.  .  It  should 
be  pointed  out  before  taking  up  this  subject,  however, 
that  the  house  fly  is  simply  a  carrier  of  disease  germs, 
and  that  it  differs  in  its  relation  to  disease  from  the 
malarial  mosquitoes,  which  are  the  necessary  secondary 
hosts  of  the  causative  organisms  of  malaria,  in  that 
only  in  mosquitoes  of  the  genus  Anopheles  can  the 
germs  complete  their  life  round  and  develop  sexual 
forms. 

In  this  they  differ  also  from  the  yellow  fever  mos- 
quito (Aedcs  calopus),  since,  although  the  causative 
organism  of  yellow  fever  has  not  yet  been  discovered, 
close  analogy  shows  that  it  must  be  a  protozoan  de- 
pendent for  its  full  development  upon  a  lodgment  in 
the  stomach  of  the  mosquito  in  question.  It  differs 
in  the  same  way  from  the  bedbug,  which  has  more  re- 
cently been  seen  to  be  probably  the  necessary  secondary 
host  of  the  causative  organism  of  kala  azar.  The  house 
fly  simply  carries  the  germs  of  disease,  either  on  its 

100 


CARRIAGE  OF  DISEASE  101 

legs  or  in  its  alimentary  canal,  just  as  these  germs  could 
be  carried  in  any  other  way — by  water,  by  shell-fish,  by 
unwashed  and  uncooked  vegetables  grown  in  land 
dressed  with  night-soil,  on  dust  particles,  or  by  personal 
contact. 

Most  of  the  wrriters  who  have  collected  data  on  this 
subject  refer  to 'the  statement  by  Sydenham,  who  is 
said  to  have  lived  between  1624  and  1689,  to  the  effect 
that  if  house  flies  are  abundant  in  the  summer  the 
autumn  will  be  unhealthy,  and  very  many  people  hold 
that  view;  but  Sydenham  was  by  no  means  the  first 
to  believe  that  the  house  fly  is  insanitary.  There  are 
many  references  to  this  insect  in  the  Hebrew  Scrip- 
tures, and  the  sanitary  regulations  of  the  camps  of  the 
children  of  Israel  in  their  march  through  the  wilder- 
ness refer  to  flies  in  terms  which  indicate  that  the  au- 
thors of  the  regulations  were  almost  as  well  posted  on 
the  subject  of  the  danger  of  flies  as  the  Japanese  sur- 
geons in  the  recent  Japanese-Russian  War.  I  have 
often  wondered  whether  the  twenty-fourth  verse  of 
the  eighth  chapter  of  Exodus,  "and  there  came  a  griev- 
ous swarm  of  flies  into  the  house  of-  Pharaoh,  and  into 
his  servants'  houses,  and  into  all  the  land  of  Egypt: 
the  land  was  corrupted  by  reason  of  the  swarm  of 
flies,"  did  not  mean  that  the  flies  corrupted  the  land, 
and  whether  there  is  not  something  very  significant  in 
the  statement  that  among  the  plagues  that  followed 
were  the  murrain  of  cattle  and  the  death  of  all  the  first- 
born of  Egypt. 

Several  of  the  great  surgeons  of  the  seventeenth  and 


102    THE  HOUSE  FLY— DISEASE  CARRIER 

eighteenth  centuries  have  referred  to  this  possibility, 
and  our  own  Leidy,  in  1871,  said  that  he  believed  that 
house  flies  were  responsible  for  the  spread  of  hospital 
gangrene  during  the  Civil  War.  In  that  same  year 
(1871)  Lord  Avebury  (then  Sir  John  Lubbock),  in 
an  article  in  the  London  Lancet,  mentioned  the  fact 
that  flies  alight  on  decomposing  matter  and  carry  se- 
cretions with  them.  He  uses  this  significant  sentence: 
"Far  from  looking  upon  them  as  dipterous  angels  danc- 
ing attendance  on  Hygeia,  regard  them  rather  in  the 
light  of  winged  sponges  spreading  hither  and  thither 
to  carry  out  the  foul  behests  of  Contagion." 

EXACT  EXPERIMENTS 

There  was,  for  a  long  time,  no  experimental  proof  of 
such  carriage.  There  have  been  outbreaks  of  disease 
and  single  cases  of  disease  where  the  carriage  of  the 
causative  organism  by  house  flies  seemed  to  be  the  best 
explanation.  Actual  experimental  proof  satisfactory  to 
the  laboratory  worker,  however,  has  been  of  recent  ac- 
quirement, and  it  will  be  well  before  entering  upon  the 
subject  of  specific  diseases  to  mention  some  of  this  work. 

One  of  the  latest  and  one  of  the  most  careful  series 
of  laboratory  observations  has  been  made  by  Doctor 
Graham-Smith  (1910).  His  experiments  covered  a 
wide  range  and  seem  to  have  been  carried  out  with  the 
utmost  pains.  The  most  satisfactory  method  of  con- 
veying his  results  is  to  give  his  conclusions  in  his  own 
words : 

"Infection  experiments  show  that  non-spore-bearing 


CARRIAGE  OF  DISEASE  103 

pathogenic  bacteria  do  not  usually  survive  more  than 
a  few  hours  (five  to  eighteen)  on  the  legs  and  wings. 
Nevertheless,  flies  allowed  to  walk  over  sterile  agar 
plates  may  cause  infection  for  several  days.  This 
seems  to  be  due  to  the  fact  that  they  frequently  attempt 
to  suck  the  surface,  and  in  so  doing  infect  it  with  fluid 
regurgitated  from  the  crop.  Within  the  crop  non- 
spore-bearing  bacteria  frequently  survive  for  several 
days,  and  they  usually  survive  even  longer  in  the 
intestine.  No  evidence  of  multiplication  in  either  of 
these  situations  has  been  obtained.  The  feces  deposited 
by  such  flies  often  contain  the  organisms  in  consider- 
able numbers  for  at  least  two  days,  and  are  frequently 
infective  for  much  longer  periods.  Anthrax  spores 
survived  for  many  days  on  the  exterior  and  in  the  ali- 
mentary canal. 

''Experiments  with  B.  prodigiosus  show  that  flies 
may  infect  sugar  forty-eight  hours  after  feeding  on 
infected  material,  and  that  clean  flies  may  infect  them- 
selves by  feeding  on  the  recent  deposits  of  infected 
flies.  In  the  few  experiments  which  were  tried,  milk 
and  meat  were  not  infected.  Flies  fed  on  anthrax 
spores  did,  however,  infect  the  syrup  which  was  given 
to  them  as  food. 

"In  the  experiments  which  have  been  described,  very 
gross  infection  was  produced  in  most  cases  by  emul- 
sions of  pure  cultures.  It  is  improbable,  however,  that 
under  natural  conditions  flies  would  often  have  the  op- 
portunity of  feeding  on  materials  which  contain  path- 
ogenic organisms  practically  in  pure  culture.  The  ef- 


104    THE  HOUSE  FLY— DISEASE  CARRIER 

fects  of  contaminating  with  non-pathogenic  and  putre- 
factive bacteria  have  as  yet  not  been  studied,  and  the 
effects  of  season,  temperature,  atmospheric  conditions, 
different  diets,  irregular  and  scanty  feeding,  and  other 
disturbing  factors  have  not  received  sufficient  attention. 

"Consequently  it  would  be  premature  to  conclude 
that  the  experiments  and  observations  described  in  this 
paper  do  more  than  indicate  that,  under  exceptionally 
favorable  conditions,  certain  bacteria  can  be  recovered 
from  the  contents  of  the  alimentary  canal  and  fecal 
deposits  of  infected  flies  for  several  days  after  infec- 
tion; and  that  these  flies  are  capable  of  infecting  cer- 
tain materials  on  which  they  feed  for  several  days.  The 
experiments  with  tubercular  sputum  and  anthracic 
blood  alone  afford  evidence  as  to  the  duration  of  life 
in  the  contents  of  the  alimentary  canal  of  pathogenic 
bacteria  taken  up  under  natural  conditions. 

'That  flies  sometimes  do  become  grossly  infected 
under  natural  conditions  is  shown  by  the  fact  that  in 
a  few  instances  pathogenic  bacteria  have  been  isolated 
from  naturally  infected  flies.  Simmons  (1892)  iso- 
lated cholera  vibrios  from  flies  which  were  captured 
in  a  post-mortem  room  in  which  the  bodies  of  persons 
dead  of  cholera  were  lying.  Tsuzuki  (1904)  was  able 
to  cultivate  the  same  organism  from  flies  captured  in 
a  cholera  house,  and  Tizzoni  and  Cattani  (1886)  ob- 
tained cultures  from  flies  caught  in  cholera  wards. 
Hamilton  (n.  1903)  and  Picker  (1902)  isolated  B. 
typhosus  from  flies  caught  in  houses  in  which  persons 
were  lying  ill  of  typhoid  fever,  and  Faichnie  (1909) 


CARRIAGE  OF  DISEASE  105 

obtained  B.  typhosus  from  a  number  of  flies  caught  in 
various  places  where  typhoid  fever  prevailed.  He 
further  showed  that  B.  typhosus  or  B.  paratyphosus 
(A)  could  be  cultivated  for  several  days  from  the  in- 
testines of  perfect  insects  which  emerged  from  larvae 
fed  on  feces  containing  these  organisms. 

"Several  observers  [Celli  (1888),  Hay  ward  (1904), 
Lord  (1904)  and  Buchanan  (1907)]  have  shown  that 
the  feces  of  flies  which  have  fed  on  tubercular  sputa 
contain  virulent  tubercle  bacilli.  Buchanan  (1907) 
demonstrated  that  flies  which  had  walked  over  nat- 
urally infected  anthracic  meat  were  capable  of  infect- 
ing agar  plates.  Yersin  (1894)  in  Hong-Kong  ob- 
served many  dead  flies  lying  about  in  his  laboratory 
where  he  made  autopsies  on  plague  animals.  He  dem- 
onstrated by  inoculation  into  animals  that  a  dead  fly 
contained  virulent  plague  bacilli. 

"Finally  the  experiments  of  Macrae  (1894)  at  the 
Gaja  jail  show  that  exposed  milk  may  become  infected 
by  the  agency  of  flies. 

"Even  these  observations  only  prove  that  cultures 
of  pathogenic  organisms  may  occasionally  be  obtained 
from  naturally  infected  flies,  and  they  do  not  afford 
conclusive  evidence  that  such  flies  are  a  frequent  source 
of  disease  in  man  by  infecting  food  materials.  Though 
many  of  the  observations  cited  by  JSTuttall  and  Jepson 
seem  to  indicate  that  flies  have  frequently  acted  as  car- 
riers of  disease,  it  has  only  once  (Macrae)  been  dem- 
onstrated that  food  has  actually  been  grossly  contam- 
inated by  them." 


106    THE  HOUSE  FLY— DISEASE  CARRIER 

Early  laboratory  experimental  work  in  the  labora- 
tory was  carried  on  in  this  country  by  Dr.  Jocelyn  Man- 
ning (1902)  of  Eau  Claire;  Wis.,  who  succeeded  in 
making  pure  cultures  from  infected  flies  of  the  fol- 
lowing bacteria :  Bacillus  pyocyaneus,  Staphyllococcus 
pyogencs  aureus,  Bacillus  typhi  abdoininalis  and  B. 
coli  communis. 

The  care  with  which  Doctor  Graham-Smith  sum- 
marizes the  results  of  his  experiments  and  the  similar 
observations  of  previous  workers,  in  order  to  preserve 
an  exactly  judicial  and  thoroughly  scientific  frame  of 
mind,  is  worthy  of  all  praise,  but  the  accumulation  of 
evidence  which  has  been  gathered  and  which  will  be 
displayed  in  our  consideration  of  the  different  diseases 
is  so  overwhelming,  both  from  the  standpoint  of  exact 
observation  and  of  sound  inference,  that  surely  every 
possible  effort  to  do  away  with  Musca  domcstica  is  am- 
ply justified  on  the  disease-bearing  ground. 

Other  laboratory  observations  have  been  made  by 
trained  bacteriologists  and  mycologists  in  the  direction 
of  the  carriage  of  micro-organisms  by  flies.  One  inter- 
esting series,  to  which  the  writer  has  referred  else- 
where, was  published  by  W.  N.  Esten  and  C.  J.  Mason 
(1908).  The  following  table  and  the  two  subsequent 
paragraphs  are  quoted  from  their  bulletin: 


CARRIAGE  OF  DISEASE 


107 


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111 


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108    THE  HOUSE  FLY— DISEASE  CARRIER 

"From  the  above  table  the  bacterial  population  of 
414  flies  is  pretty  well  represented.  The  domestic  fly 
is  passing  from  a  disgusting  nuisance  and  troublesome 
pest  to  a  reputation  of  being  a  dangerous  enemy  to  hu- 
man health.  A  species  of  mosquito  has  been  demon- 
strated to  be  the  cause  of  the  spread  of  malaria.  An- 
other kind  of  mosquito  is  the  cause  of  yellow  fever, 
and  now  the  house  fly  is  considered  an  agency  in  the 
distribution  of  typhoid  fever,  summer  complaint,  chol- 
era infantum,  etc. 

"The  numbers  of  bacteria  on  a  single  fly  may  range 
all  the  way  from  550  to  6,600,000.  Early  in  the  fly  sea- 
son the  numbers  of  bacteria  on  flies  are  comparatively 
small,  while  later  the  numbers  are  comparatively  very 
large.  The  place  where  flies  live  also  determines 
largely  the  numbers  that  they  carry.  The  average  for 
the  414  flies  was  about  1,250,000  bacteria  on  each.  It 
hardly  seems  possible  for  so  small  a  bit  of  life  to  carry 
so  large  a  number  of  organisms.  The  method  of  the 
experiment  was  to  catch  the  flies  from  the  several 
sources  by  means  of  a  sterile  fly  net,  introduce  them  into 
a  sterile  bottle,  and  pour  into  the  bottle  a  known  quan- 
tity of  sterilized  water,  then  shake  the  bottle  to  wash 
the  bacteria  from  their  bodies,  to  stimulate  the  number 
of  organisms  that  would  come  from  a  fly  falling  into  a 
lot  of  milk. 

"In  experiments  'd,'  'e/  and  T  the  bacteria  were 
analyzed  into  four  groups.  The  objectionable  class, 
coli-cero genes  type,  was  two  and  one-half  times  as 
abundant  as  the  favorable  acid  type.  If  these  flies 


Fig.   18. — Colonies  of  bacteria  on  a   sterilized  plate,   arising   from  fly 
tracks.     (From  photograph  by  William  Lyman  Underwood.) 


CARRIAGE  OF  DISEASE  109 

stayed  in  the  pig-pen  vicinity,  there  would  be  less  ob- 
jection to  the  flies  and  the  kinds  of  organisms  they 
carry,  but  the  fly  is  a  migratory  insect  and  it  visits 
everything  'under  the  sun.'  It  is  almost  impossible  to 
keep  it  out  of  our  kitchens,  dining-rooms,  cow  stables, 
and  milk  rooms.  The  only  remedy  for  this  rather 
serious  condition  of  things  is,  remove  the  pig-pen  as 
far  as  possible  from  the  dairy  and  dwelling  house.  Ex- 
treme care  should  be  taken  in  keeping  flies  out  of  the 
cow  stables,  milk  rooms  and  dwellings.  Flies  walking 
over  our  food  are  the  cause  of  one  of  the  worst  con- 
taminations that  could  occur  from  the  standpoint  of 
cleanliness  and  the  danger  of  distributing  disease 
germs." 

A  great  deal  of  work  of  this  general  nature  in  re- 
gard to  the  carriage  of  micro-organisms  by  flies  with- 
out specific  reference  as  to  the  character  of  the  organ- 
isms has  been  done  and  the  results  have  been  published 
here  and  there.  The  illustration  shown  at  Fig.  18  is 
an  early  one  made  from  a  photograph  taken  by  Wil- 
liam Lyman  Underwood  of  a  gelatin  plate  over  which  a 
fly,  captured  by  chance  in  a  room,  was  allowed  to  walk. 
On  each  spot  which  the  fly's  feet  touched  there  grew  a 
colony  of  bacteria. 

Cobb  ( 1906)  studied  the  spores  of  a  sugar  cane  fun- 
gus left  by  the  feet  of  a  fly  which  had  been  feeding 
upon  the  fungus  on  the  sides  of  a  glass  vessel.  The 
spores  from  five  of  the  tracks  on  the  glass  were  cal- 
culated and  the  number  per  track  was  found  to  be 
860,000.  A  second  calculation  gave  700,000  per  foot- 


110    THE  HOUSE  FLY— DISEASE  CARRIER 

print.  Germination  experiments  showed  that  spores 
carried  about  in  this  way,  if  deposited  in  suitable  loca- 
tions, will  germinate,  and  therefore  the  fungus  may 
sometimes  be  spread  in  this  way. 

Other  work  of  this  kind,  but  devoted  to  specific  dis- 
ease germs,  will  be  mentioned  under  the  different  dis- 
eases in  the  following  pages.  But  in  order  perhaps  to 
remove  at  once  the  impression  which  may  be  left  by  the 
cautious  words  of  Doctor  Graham-Smith,  we  may  read 
the  conclusions  of  Professor  Nuttall  and  Mr.  Jepson, 
of  Cambridge  University,  England  (1909),  both  in- 
vestigators of  the  highest  type,  after  their  critical  exam- 
ination of  the  accounts  of  experiments  made  in  this 
direction : 

"Although  there  were  some  who  at  a  very  early  date 
looked  upon  the  common  house  fly  with  suspicion,  it  is 
only  of  recent  years  that  'flies'  have  come  to  be  regarded 
as  a  serious  factor  in  the  spread  of  infective  diseases. 

"The  evidence  we  have  sifted  and  ordered  in  these 
pages  is  obviously  very  unequal  in  value,  the  most  im- 
portant relating  to  cholera  and  typhoid  fever — in  both 
cases  the  evidence  incriminating  house  flies,  of  which 
Musca  domestica  may  be  regarded  as  the  type,  appears 
to  be  quite  conclusive,  and  these  agents  will  have  to 
henceforth  receive  the  serious  attention  they  demand 
at  the  hands  of  sanitary  authorities.  From  a  practical 
point  of  view,  it  scarcely  appears  necessary  to  charge 
the  house  fly  with  more  misdoings,  bacteriological  tests 
having  shown  that  they  are  capable  of  taking  up  a 
number  of  different  pathogenic  germs  and  of  transport- 


CARRIAGE  OF  DISEASE  111 

ing  them  from  one  place  to  another.  We  regard  it  as 
certain  that  they  convey  cholera  and  typhoid  fever, 
and  we  look  forward  with  confidence  to  the  complete 
demonstration  that  they  convey  the  causative  agents 
of  infantile  diarrhea  and  of  dysentery,  always  remem- 
bering that  there  are  other  vehicles,  water,  milk,  etc.,  by 
which  these  diseases  may  be  communicated. 

"It  should  be  remembered  that  a  fly  may  cause  rela- 
tively gross  infection  of  any  food  upon  which  it  alights 
after  having  fed  upon  infective  substances,  be  they 
typhoid,  cholera,  or  diarrhea  stools.  Not  only  is  its 
exterior  contaminated,  but  its  intestine  is  charged  with 
infective  material  in  concentrated  form  which  may  be 
discharged  undigested  upon  fresh  food  which  it  seeks. 
Consequently,  the  excrement  voided  by  a  single  fly  may 
contain  a  greater  quantity  of  the  infective  agents  than, 
for  instance,  a  sample  of  infected  water.  In  potential 
possibilities  the  droppings  of  one  fly  may,  in  certain 
circumstances,  weigh  in  the  balance  as  against  buckets 
of  water  or  of  milk !" 

Surely  no  more  authoritative  or  complete  statement 
than  this  could  be  made  by  scientific  men. 

The  whole  literature  of  the  subject  of  the  transfer  of 
disease  by  insects  and  like  creatures  was  first  compre- 
hensively studied  and  collected  by  Dr.  George  H.  F. 
Nuttall  and  published  in  1900  in  an  admirable  and  ex- 
tended paper  in  the  Johns  Hopkins  Hospital  Reports, 
entitled  "On  the  Role  of  Insects,  Arachnids  and  Myria- 
pods,  as  Carriers  in  the  Spread  of  Bacterial  and  Para- 
sitic Diseases  of  Man  and  Animals.  A  Critical  and 


2    THE  HOUSE  FLY—  DISEASE  CARRIER 


Historical  Study."  This  paper  has  been  of  the  greatest 
use  to  physicians  and  to  naturalists,  and  few  general 
articles  on  this  subject  have  been  written  in  the  last 
ten  years  without  the  freest  use  of  the  data  collected  by 
Doctor  Nuttall.  In  many  cases  writers  have  gone  to 
original  sources,  but  it  is  safe  to  say  that  for  the  most 
part  they  have  learned  of  these  original  sources  through 
Doctor  Nuttall's  bibliography.  The  writer,  among 
others,  in  the  numerous  papers  he  has  published  on  this 
general  subject  during  the  years  since  1900,  has  had 
constant  occasion  to  refer  to  this  paper,  and  gladly  ex- 
presses his  obligations  to  its  author. 

More  recently  (  1909),  Doctor  Nuttall  (now  of  Cam- 
bridge University,  England)  in  collaboration  with  Mr. 
Jepson,  of  Cambridge,  has  published  a  series  of  ab- 
stracts of  literature  and  a  bibliography  relating  solely 
to  the  carriage  of  disease  by  the  house  fly  and  allied 
non-biting  flies,  which  has  been  freely  used  in  this  book 
and  will  be  later  referred  to  simply  by  references  to 
Nuttall  and  Jepson. 

TYPHOID  OR  ENTERIC  FEVER 

Typhoid  fever  is  a  disease  which  has  been  differen- 
tiated from  other  fevers  and  especially  from  typhus 
within  the  last  eighty  years.  It  is  a  disease  of  civiliza- 
tion, or  rather,  as  Doctor  Sedgwick  has  beautifully 
expressed  it,  "a  disease  of  defective  civilization."  It 
depends  upon  defective  sanitation,  and  surely,  as  Sedg- 
wick says,  defective  sanitation  means  defective  civiliza- 
tion. 


CARRIAGE  OF  DISEASE 

The  true  cause  of  the  disease  was  not  known  until 
1880,  when  it  was  discovered  by  Eberth,  and  it  was 
not  long  before  it  was  isolated  and  studied  in  pure  cul- 
ture. Technically  this  organism  is  known  as  Bacillus 
typhosus.  It  is  isolated  from  persons  who  are  sick  with 
typhoid  fever  or  who  have  been  sick  from  it,  and  only 
from  such  persons.  The  disease  which  it  causes  is  an 
intestinal  disease,  and  through  the  multiplication  of 
the  bacilli  in  the  body,  and  with  a  poisonous  substance 
which  it  produces,  conditions  are  caused  which  give 
rise  to  the  characteristic  symptoms  of  the  disease. 

Ulcerations  of  the  intestines  and  enlargements  of  the 
spleen  and  mesenteric  glands  follow,  and  the  bacilli 
frequently  invade  other  portions  of  the  body,  such  as 
the  kidney,  the  liver,  spinal  column,  the  lungs,  and 
they  have  even  been  found  in  the  brain.  They  are 
given  off  from  the  body  in  the  excrement  and  in  the 
urine.  The  characteristic  symptoms  of  the  fever  are 
an  increasing  temperature  which  fluctuates  rather  regu- 
larly, and  rose  rash  over  the  abdomen,  diarrhea  or 
constipation,  distention  of  the  intestines,  emaciation, 
and  sometimes  intestinal  hemorrhages  and  delirium. 
The  average  period  is  four  or  five  weeks,  and  this 
is  followed  by  a  long  period  of  convalescence.  Re- 
lapses are  frequent  and  are  dangerous  and  may  cause 
death.  Fatal  cases  before  a  relapse  usually  terminate 
during  the  fourth  or  fifth  week. 

Typhoid  is  thus  a  parasitic  disease,  and  its  onset 
depends  upon  the  introduction  into  the  system  of  the 
typhoid  bacillus.  Its  presence  in  the  human  body  is 


114    THE  HOUSE  FLY— DISEASE  CARRIER 

brought  about  by  eating  or  drinking  something  carry- 
ing the  bacilli.  Water,  milk,  oysters,  raw  vegetables 
may  and  do  carry  them.  They  may  be  carried  to  food 
in  other  ways :  by  contact ;  by  dust ;  and  by  certain 
household  insects,  such  as  cockroaches,  household  ants, 
and  undoubtedly  frequently  by  the  typhoid  fly,  the 
most  numerous  of  all  household  insects,  and  the  one 
which  breeds  in  substances  which  may  be  normally 
swarming  with  typhoid  bacilli. 

Suspicions  of  the  Carriage  of  Typhoid  by  Flies 

Probably  the  first  American  to  point  out  the  prob- 
able transference  of  typhoid  germs  from  box  privies 
to  food  supplies  by  the  agency  of  flies  was  Dr.  George 
M.  Kober,  of  Washington,  D.  C.  In  "Report  on  the 
Prevalence  of  Typhoid  Fever  in  the  District  of  Colum- 
bia," published  in  1895,  under  the  caption  of  "Chan- 
nels of  Invasion  and  Mode  of  Dissemination,"  Doctor 
Kober  wrote: 

"The  agency  of  flies  and  other  insects  in  carrying 
the  germs  from  box  privies  and  other  receptacles  for 
typhoid  stools  to  the  food  supply  cannot  be  ignored." 
On  the  following  page  he  gave  an  account  of  certain 
cases  on  the  Ivy  City  and  Bladensburg  Road,  in  the 
course  of  which  he  used  the  following  words,  "There 
is  abundant  evidence  of  unlawful  surface  pollution, 
*  *  *  and  as  the  germs  find  a  suitable  soil  in  such 
surroundings,  it  is  possible  that  the  flies  which  abound 
wherever  surface  pollution  exists  may  carry  the  germs 
into  the  houses  and  contaminate  the  food.  *  *  * 


CARRIAGE  OF  DISEASE  115 

There  was  nothing  in  common  in  the  milk  supply  of 
the  different  houses,  and  as  there  was  no  well  liable 
to  contamination  from  the  first  source,  it  is  not  im- 
probable that  the  infection  was  conveyed  in  the  man- 
ner indicated." 

Writing  of  nine  cases  occurring  in  a  certain  locality 
in  Washington,  he  says,  "There  was  nothing  in  com- 
mon in  the  milk  supply,  and  the  fact  that  the  cases  oc- 
curred at  considerable  intervals  indicates  with  more 
or  less  certainty  that  the  first  case  was  a  focus  of  in- 
fection; but  how  the  germs  were  carried,  unless  by 
flies,  or  through  the  air,  is  a  matter  impossible  to  de- 
termine." Later,  in  writing  of  methods  for  the  dis- 
posal of  human  excreta,  he  says,  "These  boxes,  even 
if  there  are  no  wells,  are  still  a  source  of  danger  in 
so  far  as  they  favor  the  transmission  of  germs  by 
means  of  infected  flies."  In  his  conclusion,  he  writes, 
"A  large  percentage  of  the  cases  occurred  in  houses 
supplied  with  box  privies  which,  apart  from  being  an 
important  cause  of  soil  pollution,  are  believed  to  be 
otherwise  instrumental  in  the  dissemination  of  germs, 
chiefly  through  the  agency  of  flies." 

The  attention  of  all  interested  was  riveted  to  the 
question  of  the  agency  of  flies  by  the  results  of  the 
investigations  carried  on  during  the  Spanish-American 
War  in  1898.  In  his  first  circular  of  directions  to  army 
surgeons,  the  Surgeon-General  of  the  Army,  Dr. 
George  M.  Sternberg,  gave  explicit  directions  regard- 
ing sinks,  which,  if  followed  carefully,  would  have  pre- 
vented the  spread  of  typhoid  by  flies,  and  he  definitely 


116    THE  HOUSE  FLY— DISEASE  CARRIER 

stated  that  no  doubt  typhoid  fever  and  camp  diarrhea 
are  frequently  communicated  to  soldiers  in  camp 
through  the  agency  of  flies  which  swarm  about  fecal 
matter  and  directly  convey  infectious  material  attached 
to  their  feet  or  contained  in  their  excreta  to  the  food 
which  is  exposed  while  being  prepared  at  the  common 
kitchen  or  while  being  served  in  the  mess  tent.  These 
directions  from  the  Surgeon-General,  however,  were 
ignored,  with  the  result  that  the  world  got  its  first 
large-scale  and  convincing  demonstration  of  the  car- 
riage of  typhoid  by  flies,  although  the  laboratory 
method  was  not  used  in  this  demonstration. 

Inferential  Proof 
<j 

One  of  the  volunteer  surgeons,  Dr.  M.  A.  Veeder, 

who  had  already  been  interested  in  the  subject,  wrote 
articles  before  the  close  of  1898  calling  attention  to 
observations  upon  flies  traveling  back  and  forth  between 
the  latrines  and  the  cooking  tents  in  concentration 
camps  in  the  Southern  United  States,  and  concluded 
that  the  conveyance  of  typhoid  infection  in  the  man- 
ner indicated  "is  the  chief  factor  in  decimating  the 
army."  Before  Veeder's  articles  had  been  published, 
typhoid  was  rampant  in  many  of  the  concentration 
camps,  and  an  army  typhoid  commission  was  appointed 
in  August  of  that  year,  consisting  of  Drs.  Walter  Reed, 
U.  S.  A. ;  Victor  M.  Vaughan,  U.  S.  V. ;  and  E.  O. 
Shakespeare,  U.  S.  V.  These  men  were  all  of  high 
scientific  standing,  the  chairman  being  the  now  fa- 
mous discoverer  of  the  true  etiology  of  yellow  fever. 


CARRIAGE  OF  DISEASE  117 

The  investigation  was  thorough,  and  at  the  annual 
meeting  of  the  American  Medical  Association  in  June, 
1900,  Doctor  Vaughan  presented  a  paper  entitled  ''Con- 
clusions Reached  after  a  Study  of  Typhoid  Fever 
among  American  Soldiers  in  1898."  This  report  com- 
prised fifty-three  categorical  conclusions.  The  one  re- 
lating to  flies  was  as  follows : 

"27.  Flies  undoubtedly  served  as  carriers  of  the  in- 
fection. 

"My  reasons  for  believing  that  flies  were  active  in 
the  dissemination  of  typhoid  may  be  stated  as  fol- 
lows: 

"a.  Flies  swarmed  over  infected  fecal  matter  in  the 
pits  and  then  visited  and  fed  upon  the  food  prepared 
for  the  soldiers  at  the  mess  tents.  In  some  instances 
where  lime  had  recently  been  sprinkled  over  the  con- 
tents of  the  pits,  flies  with  their  feet  whitened  with  lime 
were  seen  walking  over  the  food. 

"b.  Officers  whose  mess  tents  were  protected  by 
means  of  screens  suffered  proportionately  less  from  ty- 
phoid fever  than  did  those  whose  tents  were  not  so 
protected. 

"c.  Typhoid  fever  gradually  disappeared  in  the  fall 
of  1898,  with  the  approach  of  cold  weather,  and  the 
consequent  disabling  of  the  fly. 

"It  is  possible  for  the  fly  to  carry  the  typhoid  bacillus 
in  two  ways.  In  the  first  place,  fecal  matter  containing 
the  typhoid  germ  may  adhere  to  the  fly  and  be  mechan- 
ically transported.  In  the  second  place,  it  is  possible 
that  the  typhoid  bacillus  may  be  carried  in  the  digestive 


118    THE  HOUSE  FLY— DISEASE  CARRIER 

organs  of  the  fly  and  may  be  deposited  with  its  excre- 
ment." 

There  were  many  other  important  conclusions  which 
bear  upon  the  fly  question.  For  example,  it  was  shown 
that  every  regiment  in  the  United  States  service  in 
1898  developed  typhoid  fever,  nearly  all  of  them  within 
eight  weeks  after  assembling  in  camps.  It  not  only 
appeared  in  every  regiment  in  the  service,  but  it  be- 
came epidemic  both  in  small  encampments  of  not  more 
than  one  regiment  and  in  the  larger  ones  consisting  of 
one  or  more  corps.  All  encampments  located  in  the 
Northern  as  well  as  in  the  Southern  States  exhibited 
typhoid  in  epidemic  form.  The  miasmatic  theory  of 
the  origin  of  typhoid  fever  and  the  pythogenic  theory* 
were  not  supported  by  the  investigations  of  the  com- 
mission, but  the  doctrine  of  the  specific  origin  of  fever 
was  confirmed.  The  conclusion  was  reached  that  the  fe- 
ver is  disseminated  by  the  transference  of  the  excretions 
of  an  infected  individual  to  the  alimentary  canals  of 
others  and  that  a  man  infected  with  typhoid  fever  may 
scatter  the  infection  through  every  latrine  or  regiment 
before  the  disease  is  recognized  in  himself,  while  germs 
may  be  found  in  the  excrement  for  a  long  time  after 
the  apparent  complete  recovery  of  the  patient.  Infected 
water  was  not  an  important  factor  in  the  spread  of 
typhoid  in  the  national  encampments  of  1898,  but  about 

This  theory  is  founded  upon  the  belief  that  the  colon  germ 
may  undergo  a  ripening  process  by  means  of  which  its  virulence 
is  so  increased  and  altered  that  it  may  be  converted  into  the 
typhoid  bacillus  or  at  least  may  become  the  active  agent  in  the 
causation  of  typhoid  fever. 


CARRIAGE  OF  DISEASE  119 

one-fifth  of  the  soldiers  in  the  national  encampments 
in  the  United  States  during  that  summer  developed 
this  disease,  while  more  than  eighty  per  cent,  of  the 
total  deaths  were  caused  by  typhoid. 

About  the  same  time  that  Doctor  Vaughan's  report 
was  presented,  Dr.  R.  H.  Quill,  in  a  "Report  on  an 
outbreak  of  Enteric  Fever  at  Diyatalawa  Camp,  Ceylon, 
among  the  Second  King's  Royal  Rifles  during  the 
period  they  acted  as  guard  over  the  Boer  prisoners  of 
the  war,"  stated  that  "during  the  whole  period  that 
enteric  fever  was  rife  in  the  Boer  camp,  flies  in  that 
camp  amounted  almost  to  a  plague,  the  military  camp 
being  similarly  infested,  though  to  a  lesser  extent." 

During  the  Boer  War  again  and  again  the  connec- 
tion between  flies  and  enteric  fever  was  noted.  Nut- 
tall  and  Jepson  have  collected  some  significant  quota- 
tions from  different -writers  of  that  period.  These  may 
be  quoted  as  follows : 

"Tooth  and  Calverley  (1901,  p.  73),  writing  of  ty- 
phoid in  camps  during  the  South  African  War,  state 
that  'In  a  tent  full  of  men,  all  apparently  equally  ill, 
one  may  almost  pick  out  the  enteric  cases  by  the  masses 
of  flies  that  they  attract.  This  was  very  noticeable  at 
Modder  River,  for  at  that  time  there  were  in  many 
tents  men  with  severe  sunstroke  who  resembled  in  some 
ways  enteric  patients,  and  it  was  remarkable  to  see  how 
the  flies  passed  over  them  to  hover  round  and  settle  on 
the  enterics.  The  moment  an  enteric  patient  put  out 
his  tongue,  one  or  more  flies  would  settle  on  it.' 

"The  authors  further  state  that:  'At  Bloemfontein 


120    THE  HOUSE  FLY— DISEASE  CARRIER 

the  flies  were  a  perfect  pest ;  they  were  everywhere,  and 
in  and  on  every  article  of  food.  It  is  impossible  not  to 
regard  them  as  important  factors  in  the  dissemination 
of  enteric  fever.  Our  opinion  is  further  strengthened 
by  the  fact  that  enteric  fever  in  South  Africa  practi- 
cally ceases  every  year  with  the  cold  weather,  and  this 
was  the  case  at  Bloemfontein.  For  though  the  days 
after  10  A.M.  were  as  an  English  summer  day,  and  the 
temperature  in  our  tents  was  rarely  below  70°  and 
often  about  80°  F.,  the  nights  were  very  cold,  and 
often  frosty,  and  with  the  cold  nights  the  flies  disap- 
peared. It  seemed  to  us  that  the  cold  weather  reduced 
the  number  of  enteric  cases  by  killing  these  pests/ 

"Smith  (1903),  also  writing  of  South  Africa,  states 
that  a  neglected  trench  'becomes  an  open  privy  with  an 
infected  surface  soil  around  it;  the  flies  browse  in  it 
in  the  daytime  and  occupy  the  men's  tents  at  night. 
On  visiting  a  deserted  camp  during  the  recent  campaign 
it  was  common  to  find  half  a  dozen  or  so  open  latrines 
containing  a  fetid  mass  of  excreta  and  maggots;  this 
because  the  responsible  persons  so  often  failed  to  com- 
ply with  the  regulations  for  encampments  by  filling  in 
latrines  on  the  departure  of  the  troops.' 

"Austen  (1904,  p.  656)  vividly  recalls  'a  latrine  in 
a  certain  standing  camp  in  South  Africa  during  the 
late  war,  in  which  the  conditions  as  regards  flies  were 
precisely  as  described  by  Major  Smith.  It  is  only  fair 
to  say  that  the  ground  was  extremely  hard  and  stony, 
so  that  very  little  soil  was  available  for  covering  up 
the  contents  of  the  trench.  On  visiting  the  latrine 


CARRIAGE  OF  DISEASE 

after  it  had  been  left  undisturbed  for  a  short  time,  a 
buzzing  swarm  of  flies  would  suddenly  arise  from  it 
with  a  noise  faintly  suggestive  of  the  bursting  of  a 
percussion  shrapnel  shell.  The  latrine  was  certainly 
not  more  than  one  hundred  yards  from  the  nearest 
tents,  if  so  much,  and,  at  meal  times,  men's  mess  tins, 
etc.,  were  always  invaded  by  flies.  A  tin  of  jam  in- 
cautiously left  open  for  a  few  minutes  became  a  seeth- 
ing mass  of  flies  (chiefly  Pycnosoma  chloropyga 
Wied.),  completely  covering  the  contents/ 

"F.  Smith  (1903,  p.  331)  refers  to  his  experience  in 
the  South  African  War  in  seeing  flies  go  from  bed- 
pans to  milk,  etc.,  and  discusses  in  detail  methods  of 
sewage  disposal  in  warm  countries." 

Still  later  observations  of  a  similar  character  have 
been  made,  not  in  war  times  but  in  times  of  peace,  at 
army  stations  and  encampments  during  practice  maneu- 
vers. A  report  by  Maj.  C.  F.  Wanhill  on  typhoid  con- 
ditions in  Bermuda,  for  example,  shows  that  from  1893 
to  1902  Bermuda  had  the  highest  enteric  fever  rate 
among  the  troops  of  any  command  occupied  by  British 
troops.  Major  Wanhill  was  placed  in  charge  in  1904, 
and  in  two  years  almost  wiped  the  disease  out.  He 
considered  that  carriage  of  the  germs  by  flies  was  the 
most  important  mode  of  transfer. 

With  regard  to  the  British  army  stations  in  India, 
the  Journal  of  the  Royal  Army  Medical  Corps  for  the 
past  six  years  has  contained  many  suggestive  and  im- 
portant articles  written  by  different  members  of  the 
Royal  Army  Medical  Corps  which  emphasize  to  a  strik- 


THE  HOUSE  FLY— DISEASE  CARRIER 

ing  degree  the  attention  which  is  now  being  paid  to 
the  house  fly  and  its  near  relative  Musca  entccniata. 
More  or  less  definite  proof  of  the  connection  between 
flies  and  enteric  fever  is  given  again  and  again  and 
great  attention  has  been  paid  to  the  question  of  latrines. 
For  example,  Lieut.  Col.  F.  W.  C.  Jones  (1907)  uses 
the  following  phraseology :  " Believing  as  we  do  that 
flies  are  the  chief  carriers  of  enteric  fever  in  India,  any 
plan  which  gets  rid  of  them  is  worthy  of  considera- 
tion." And  then  the  author  proceeds  to  discuss  the 
relative  merits  of  incineration  of  excreta  and  other 
plans.  Of  course  the  officers  of  the  army  have  con- 
trol over  their  camps,  but  in  India  great  difficulty  has 
been  experienced  in  enforcing  the  proper  views  upon 
high-caste  natives. 

Colonel  Jones,  in  the  article  just  cited,  found  a  cer- 
tain line  of  reasoning  very  useful,  not  only  with  high- 
caste  native  officers  but  with  men  on  maneuvers.  This 
consisted  in  an  explanation  of  the  meaning  of  the  word 
kakophagy,  which,  being  translated  from  the  Greek, 
means  excrement-eating.  Colonel  Jones  writes.  "I  pre- 
sume no  one  wishes  to  be  a  kakophagist ;  yet  we  are  so 
in  spite  of  ourselves,  if  flies  bred  in  filth  pits  alight  on 
our  food  just  before  we  eat  it."  The  high-caste  officers 
at  first  looked  upon  sanitary  measures  as  being  only 
meant  to  worry  them,  but  Colonel  Jones  got  several  of 
them  together  and  to  the  best  of  his  ability  explained 
that  men  who  took  no  precautions  in  camps  to  prevent 
the  breeding  of  flies  must  of  necessity  be  kakophagists. 
He  found  that  this  appealed  to  them  most  strongly,  and 


CARRIAGE  OF  DISEASE 

he  had  no  further  trouble.  Does  it  not  at  once  occur 
to  the  reader  that  to  almost  every  American  this  ob- 
jectionable term  might  with  justice  be  applied? 

Any  quantity  of  inferential  proof  continues  to  ac- 
cumulate. The  Merchants'  Association  of  New  York 
has  accumulated  the  opinions  of  many  health  officers 
and  physicians  as  well  as  of  entomologists  and  has  pub- 
lished them  in  convincing  form.  At  the  December, 
1910,  meeting  of  the  American  Association  for  the  Ad- 
vancement of  Science,  at  Minneapolis,  Prof.  F.  L. 
Washburn  gave  a  lecture  entitled  "The  Typhoid  Fly 
on  the  Minnesota  Iron  Range,"  in  which  he  gave  the 
results  of  a  careful  study  of  the  conditions  in  certain 
mining  towns  in  that  State  during  the  summer  of  1910, 
in  which  the  conditions  were  such  as  to  make  it 
perfectly  plain  that  the  main  etiological  factor  in 
the  typhoid  epidemic  then  existing  was  Musca  domes- 
tica. 

The  length  of  time  that  the  typhoid  bacillus  will  live 
in  various  substances  from  which  it  is  likely  to  be  car- 
ried by  flies  to  food  substances  is  important  and  has 
received  some  consideration.  The  length  of  time  in 
which  the  bacillus  will  live  in  food  substances,  how- 
ever, is  even  more  deserving  of  consideration.  Milk, 
commonly  charged  with  the  carriage  of  typhoid  fever, 
is  hardly  of  the  greatest  importance  in  this  connection, 
since  milk  is  such  a  short-lived  food  substance  itself, 
although  it  is  often  contaminated  with  typhoid  bacilli 
through  the  washing  of  the  vessels  which  contain  it 


THE  HOUSE  FLY— DISEASE  CARRIER 

in  contaminated  water  and  by  infected  flies  dropping 
into  it. 

When  it  comes  to  butter  and  cheese,  however,  we 
have  long-lived  foods,  and  the  possibilities  of  their  con- 
tamination by  flies  and  their  subsequent  use  is  of  espe- 
cial interest,  and  more  particularly  as  to  the  length  of 
time  that  they  will  harbor  virulent  germs  gained  in  this 
way  or  in  any  other. 

Dr.  John  R.  Mohler,  of  the  Bureau  of  Animal  In- 
dustry of  the  United  States  Department  of  Agriculture, 
informs  the  writer  that  investigations  made  in  his  of- 
fice show  that  typhoid  bacilli  will  live  in  butter  under 
common  market  conditions  for  151  days,  and  still  be 
able  to  grow  when  transferred  to  suitable  conditions. 
In  milk  under  market  conditions  they  retain  active  mo- 
tility  for  twenty  days,  after  which  time  there  is  a  lessen- 
ing in  numbers  until  on  the  forty-third  day  of  the  test 
they  disappear  from  view.  At  certain  seasons  of  the 
year  large  numbers  of  flies  collect  upon  the  vats  in 
which  milk  and  cream  are  being  stored  in  dairies  and 
creameries;  many  flies  fall  in,  their  bodies  being 
strained  out  when  the  cream  is  sent  to  the  churn.  If 
any  of  these  flies  carry  typhoid  bacilli  these  are  washed 
off  by  the  milk  and  remain  in  the  butter  or  cheese  made 
from  it.  Thus  the  eating  of  butter  contaminated  in 
this  way  may  account  for  very  many  cases  of  typhoid 
fever  the  cause  of  which  cannot  otherwise  be  traced. 


CARRIAGE  OF  DISEASE 


Exact  Proof 

From  the  laboratory  point  of  view,  a  number  of  ex- 
act experiments  have  been  made,  and  we  quote  the  fol- 
lowing paragraphs  from  Nuttall  and  Jepson  : 
¥  "Celli  (1888)  fed  flies  with  pure  cultures  of  the 
Bacillus  typhosus  and  examined  their  contents  and  de- 
jections microscopically  and  culturally.  Vlnoculations 
on  animals  were  also  made,  proving,  as  he  supposed, 
that  the  bacilli  which  passed  through  flies  were  viru- 
lent. (He  made  similar  observations  with  the  Spiril- 
lum Finkler-Prior.)* 

"As  Ficker  (1903,  p.  274)  properly  points  out, 
Celli's  statement  has  less  value  to-day,  since  at  the  time 
he  carried  out  his  experiments  no  suitable  means  ex- 
isted for  properly  differentiating  B.  typhosus  from 
other  organisms  of  similar  character.  W 

"Firth  and  Horrocks  (1902)  kept  M.  domestica 
(also  blue-bottles)  in  a  large  box  measuring  four  by 
three  feet,  with  one  side  made  of  glass.  They  were 
fed  on  material  contaminated  with  cultures  of  B. 
typhosus.  Agar  plates,  litmus,  glucose  broth,  and  a 
sheet  of  clean  paper  were  at  the  same  time  exposed  in 
the  box.  After  a  few  days  the  plates  and  broth  were 
removed  and  incubated  with  a  positive  result.  The 
flies'  excreta  on  the  paper  yielded  B.  coli  almost  in  pure 
culture.  In  a  second  experiment  some  fresh  typhoid 
stool  to  which  a  typhoid  culture  had  been  added  was 
dusted  with  earth  and  served  as  the  infective  material  ; 
colonies  of  B.  typhosus  appeared  on  the  plates.  In  a 


126    THE  HOUSE  FLY— DISEASE  CARRIER 

third  experiment  the  infected  flies  were  captured  and 
killed.  By  means  of  sterile  forceps  their  heads,  wings, 
legs,  and  bodies  were  separated  and  respectively  placed 
in  sterile  broth.  Sub-cultures  of  the  broth  all  gave  a 
positive  result.  The  authors  conclude  that  M.  domcs- 
tica  can  convey  B.  typhosus  from  infected  sources  to 
objects  upon  which  they  walk,  rest,  or  feed,  and  that 
bacilli  adhere  to  the  external  parts  of  flies.  'It  has  not 
been  proved  that  the  enteric  bacillus  passes  through  the 
digestive  tract  of  the  fly/ 

"Hamilton  (II.  1903)  in  Chicago,  caught  eighteen 
flies  in  and  about  houses  and  rooms  occupied  by  ty- 
phoid cases,  and  states  that  she  found  B.  typhosus  in 
five  of  them. 

"Ficker  (1903)  caught  flies  in  a  house  in  Leipzig 
where  eight  cases  of  typhoid  had  occurred.  He  isolated 
B.  typhosus  from  the  flies.  He  carried  out  experiments 
with  M.  domestica  kept  in  ten-liter  flasks  into  which  he 
introduced  some  sugar,  strips  of  filter  paper,  and  cul- 
ture of  typhoid  bacilli  in  bouillon.  This  was  spread 
on  the  glass  and  partly  absorbed  by  the  filter  paper. 
After  eighteen  to  twenty-four  hours  the  flies  were  trans- 
ferred to  clean  flasks.  He  found  the  flies  to  survive 
over  four  weeks  in  captivity  if  protected  from  the  cold 
and  fed  on  sugar,  bread  and  water,  or  milk.  He  notes 
that  flies  may  all  die  during  a  cold  night,  irrespective 
of  typhoid,  bacilli  being  present  in  their  food.  The 
flies  were  transferred  to  clean  flasks  every  two  or  three 
days.  The  flies  to  be  examined  were  etherized  and 
rubbed  up  in  a  mortar — the  crushed  material  being 


CARRIAGE  OF  DISEASE  127 

used  for  making  the  plates  on  gelatin  and  special  media. 
B.  typhosus  was  recovered  from  the  flies  twenty-three 
days  after  they  had  been  infected. 

"Buchanan  (1907)  allowed  M.  domestica  to  walk 
over  the  surface  of  a  Petri  dish  smeared  with  typhoid 
dejections.  The  flies  (number?)  were  immediately 
afterwards  allowed  to  walk  over  the  surface  of  media 
in  Petri  dishes.  Naturally,  some  plates  became  in- 
fected. 

"The  evidence  regarding  the  part  that  flies  may  play 
in  the  spread  of  typhoid  fever  may  therefore  be  ac- 
cepted as  quite  conclusive/* 

In  addition  to  the  experiments  by  Nuttall  and  Jep- 
son  given  above  should  be  mentioned  the  experiments 
recorded  by  Major  N.  Faichnie  ( 1909) .  Major  Faichnie 
states  that  he  was  recently  sent  to  investigate  a  small 
outbreak  of  enteric  fever  at  Kamptee,  where  he  was 
obliged  to  suspect  flies,  after  excluding  all  other  causes. 
Flies  were  not  over-numerous,  but  twelve  from  the 
artillery  lines  were  mashed  up  in  sterile  salt  solution, 
and  Bacillus  typhosus  was  separated.  Twelve  flies  from 
the  infantry  kitchen  were  then  captured.  Each  was 
transfixed  with  a  sterile  needle,  passed  two  or  three 
times  through  a  flame  until  the  legs  and  wings  were 
scorched,  and  was  then  put  in  a  normal  salt  solution 
and  stirred.  After  this  they  were  mashed  up  and  B. 
typhosus  was  found.  Before  mashing  it  was  not  found. 
The  demonstration  that  the  bacillus  was  present  in  the 
intestines  was  therefore  good.  His  conclusions  are 
that  while  experience  seems  to  show  that  infection  con- 


128    THE  HOUSE  FLY— DISEASE  CARRIER 

veyed  by  flies'  legs  is  not  common  in  times  of  peace, 
"infection  by  the  excrement  of  flies  bred  in  infected 
material  explains  many  conclusions  formerly  difficult 
to  accept." 

Chronic  Carriers 

It  becomes  necessary  at  this  stage  to  discuss  the  ques- 
tion of  persons  who  become  chronic  carriers  of  typhoid 
germs,  giving  them  out  in  their  excreta  and  in  their 
urine  for  perhaps  many  years.  The  application  of  this 
phenomenon  to  the  fly  question  will  be  dealt  with  later. 
It  was  known  in  the  United  States  prior  to  the  Span- 
ish-American War  that  typhoid  patients  would  give  out 
bacilli  in  this  way  before  the  disease  was  diagnosed, 
and  it  was  also  known  that  some  of  them  would  give 
out  the  germs  for  perhaps  several  weeks  after  the  fever 
abated  and  the  patient  was  practically  cured.  And  of 
course  the  walking  typhoid  or  "ambulatory  enteric" 
was  known  to  exist;  that  is  to  say,  slight  cases  which 
did  not  bring  the  patient  to  bed  but  during  which  germs 
must  have  been  given  off.  True  chronic  carriers  were 
not  known  in  this  country  at  that  time,  and  the  develop- 
ment of  this  extremely  important  phase  of  the  typhoid 
question  has  been  a  recent  one.  The  phenomenon  was 
known  in  Germany  before  it  was  brought  vividly  to 
the  attention  of  the  American  people. 

The  first  case  here  to  receive  general  notice  was  that 
of  "Typhoid  Mary,"  an  Irish  cook,  who  was  discovered 
by  Dr.  George  A.  Soper,  of  New  York.  She  had  been 
cook  with  a  family  on  Long  Island,  and  during  the 
summer  of  1906  several  cases  of  typhoid  occurred.  The 


CARRIAGE  OF  DISEASE  129 

writer  was  consulted,  and  advised  that  Doctor  Soper  be 
called  in  to  make  a  thorough  investigation.  The  results 
of  Doctor  Soper' s  search  were  most  interesting.  Af- 
ter studying  every  possible  source  with  absolutely  nega- 
tive results,  the  proper  examinations  were  begun,  and 
it  was  discovered  that  Mary,  the  cook,  was  a  chronic 
carrier.  Her  past  history  was  looked  into,  and  it  was 
found  that  for  several  years  there  had  been  typhoid 
cases  in  nearly  every  family  who  had  engaged  her. 
She  was  immediately  isolated,  and  kept  in  custody  for 
three  years.  Then  she  was  released,  promising  never 
again  to  engage  as  cook  and  to  report  at  frequent 
intervals.  She  returned  after  four  months  saying  that 
she  could  get  no  work  and  was  placed  by  the  New  York 
City  Department  of  Health  in  one  of  the  laundries  of 
a  public  institution,  where  she  still  remains. 

Much  space  was  devoted  to  accounts  of  this  case  in 
the  daily  newspapers  and  other  publications  at  the  time, 
and  about  that  time  and  subsequently  many  investi- 
gators began  to  look  into  the  general  subject  of  typhoid 
carriers,  with  remarkable  results.  For  example,  a  dairy 
maid  was  found  at  Killworth,  England,  in  1909, 
through  the  investigations  which  followed  a  typhoid 
outbreak.  It  was  discovered  that  she  had  had  the  fever 
in  1903,  and  that  families  with  whom  she  subsequently 
lived  had  typhoid  cases.  Finally  she  became  attached 
to  a  dairy  which  furnished  milk  to  an  army  post,  and 
when  the  milk  was  not  boiled  many  cases  of  typhoid 
resulted. 

In  another  instance  an  epidemic  of  typhoid  in  the 


130    THE  HOUSE  FLY— DISEASE  CARRIER 

Tenth  German  Army  Corps  in  the  summer  of  1909 
was  traced  to  a  chronic  carrier  in  the  case  of  a  woman 
who  prepared  vegetables  and  who  had  assisted  in  the 
preparation  of  vegetable  salads.  The  typhoid  bacillus 
grows  on  the  surface  of  potatoes  readily,  and  this  ac- 
counted for  the  outbreak,  on  the  necessary  supposition, 
that  the  woman  was  of  uncleanly  habits.  The  curious 
point  in  this  case  was  that  she  had  had  typhoid  thirty- 
six  years  previously  for  the  only  time.  In  the  same 
summer  there  was  an  epidemic  of  the  fever  in  George- 
town, D.  C.  This  was  traced  by  milk  routes  to  a  cer- 
tain milk  dealer,  who  was  a  woman  and  who  on  ex- 
amination was  shown  to  be  a  chronic  carrier. 

In  the  same  year,  Aldrich,  in  the  Journal  of  the 
Royal  Army  Medical  Corps  for  September,  page  225, 
made  the  generalization  that  the  combined  observations 
of  a  large  number  of  investigators  in  various  countries 
showed  that  about  three  per  cent,  of  the  convalescent 
typhoid  patients  become  chronic  carriers,  and  of  these 
eighty  per  cent,  are  women.  About  this  time  the  Ger- 
man Government  conducted  an  anti-typhoid  campaign 
in  Southwest  Germany,  and  in  his  report  Klinger 
showed  that  400  chronic  carriers  were  found  and  that 
there  were  probably  others. 

Earlier  than  this,  Dr.  W.  G.  Savage  (1907)  made 
three  points  of  interest  in  this  connection :  ( i )  Ty- 
phoid bacilli  are  frequently  excreted  in  the  urine  in 
about  twenty  per  cent  of  the  cases,  but  the  obvious 
practical  measures  resulting  from  this  knowledge  are 
not  habitually  taken.  (2)  Typhoid  bacilli  may  persist 


CARRIAGE  OF  DISEASE  131 

in  the  body  and  be  found  in  the  feces  and  gall  blad- 
der long  after  all  clinical  symptoms  have  ceased;  it 
appears  that  women  form  a  large  percentage  of  chronic 
bacilli  carriers;  sixteen  out  of  twenty-two  cases  (Lutz) 
and  nine  out  of  twelve  cases  (Klinger).  (3)  Typhoid 
bacilli  may  be  found  in  the  excreta  of  healthy  persons 
who  have,  apparently  never  suffered  from  typhoid 
fever;  they  have  been  in  contact  with  cases  of  typhoid 
and  are  analogous  to  the  contact  cases  of  diphtheria 
outbreaks. 

Nature,  in  a  review  of  scientific  memoirs  by  officers 
of  the  Medical  and  Sanitary  Departments  of  the  Gov- 
ernment in  India,  No.  32,  Calcutta,  1908  (Review,  Na- 
ture, November  5,  1908,  p.  21),  shows,  as  a  result  of 
this  Indian  work,  that  the  typhoid  bacillus  continues 
to  be  excreted  for  long  periods  in  the  urine  and  feces 
of  a  certain  percentage  of  patients  convalescent  from 
enteric  fever,  the  number  in  the  urine  being  very  large 
and  the  excretion  being  markedly  intermittent.  The 
general  conclusion  arrived  at  was  that  the  problem  of 
the  prevention  of  enteric  fever  among  the  British  troops 
in  India  is  the  detection  and  isolation  of  the  individual 
harboring  the  Bacillus  typhosus. 

As  a  matter  of  course,  the  typhoid  patient  himself 
is  a  much  more  frequent  cause  of  infection  than  the 
healthy  typhoid  carrier.  Klinger,  in  the  report  of  the 
anti-typhoid  campaign  in  Southwest  Germany,  pre- 
viously referred  to,  found  that  the  typhoid  patient  was 
the  source  of  infection  in  1,272  cases  and  the  healthy 
typhoid  carrier  in  125  cases.  He  concluded  therefore 


132    THE  HOUSE  FLY— DISEASE  CARRIER 

that  typhoid  patients  should  be  considered  the  chief 
source  and  that  this  was  due  to  their  being  not  only 
more  numerous  than  the  carriers,  but  also  to  the  fact 
that  the  germs  passed  by  them  are  usually  more  dan- 
gerous. On  the  other  hand,  every  infection  by  a  ty- 
phoid carrier  may  be  the  first  in  a  long  series  of  cases ; 
in  fact,  he  may  be  responsible  for  a  whole  epidemic. 
His  importance  cannot  be  over-estimated.  As  Klinger 
says,  "He  is  an  important  factor,  and  typhoid  houses 
and  typhoid  areas  seem  to  be  his  work." 

In  an  article  in  the  Boston  Medical  and  Surgical 
Journal*  we  find  the  following  very  interesting  state- 
ments and  reports  of  cases  of  this  sort,  that  mentioned 
in  the  final  paragraph  evidently  being  Typhoid  Mary : 

"It  is  asserted  by  Kutscher  that,  in  Southwestern 
Germany,  direct  contact  is  a  more  important  factor  in 
the  spread  of  typhoid  fever  than  polluted  water,  and 
that  about  four  per  cent,  of  typhoid  patients  become 
chronic  carriers  of  the  specific  bacilli,  which  they  ex- 
crete in  both  urine  and  feces,  sometimes  for  long  peri- 
ods. Doerr.  for  example,  cites  cases  reported  by 
Drober  and  Hunner,  in  which  the  bacilli  were  isolated 
from  the  gall  bladder  seventeen  and  twenty  years  after 
recovery,  and  Lentz  asserts  that  if  after  ten  weeks  from 
convalescence  the  excretion  of  the  bacilli  has  not  ceased, 
it  will  most  likely  continue  permanently  and  uninter- 
ruptedly, in  spite  of  medication.  He  cites  a  number  of 
cases  in  which,  after  ten,  thirty,  and  even  forty-two 

*The  exact  reference  to  this  important  article  has  been  lost  and 
cannot  be  found. 


CARRIAGE  OF  DISEASE  133 

years  after  recovery,  the  excretion  continued.  Levy 
and  Kayser  report  that  in  the  autumn  of  1905  a  num- 
ber of  cases  of  typhoid  fever  occurred  in  an  insane 
asylum,  in  which  two  years  previously  an  inmate  had 
had  the  disease  and  had  recovered.  On  the  appear- 
ance of  these  later  cases,  this  person  was  examined  and 
was  found  to  be  excreting  the  bacilli  in  her  f eces.  Fur- 
ther examinations  were  made  at  intervals  of  several 
weeks,  and  the  bacilli  were  found  ten  times.  In  Oc- 
tober, 1906,  she  died  of  a  typhoid  bacillary  septicemia, 
due  to  auto-infection  from  the  gall  bladder;  and  on 
autopsy  the  bacilli  were  isolated  from  the  spleen,  liver, 
bile,  wall  of  the  gall  bladder  and  from  the  interior  of 
a  large  gall-stone. 

"A  somewhat  similar  case  is  reported  by  Nieter  and 
Liefmann,  also  from  an  insane  asylum  in  which  the 
disease  had  been  endemic  for  many  months.  A  patient 
dead  of  chronic  dysentery  was  examined  and  typhoid 
bacilli  were  found  in  the  intestines  and  in  pure  culture 
in  the  gall  bladder,  in  which  were  gall-stones.  Among 
250  inmates  were  found  seven  typhoid  carriers. 

"Klinger  found,  among  1,700  persons,  twenty-three 
typhoid  carriers,  ranging  in  age  from  eighteen  months 
to  sixty  years,  eleven  of  whom  had  no  typhoid  history. 
Of  842  convalescents  from  the  disease,  sixty-three,  or 
thirteen  and  one-tenth  per  cent,  were  found  to  be  excret- 
ing the  bacilli,  and  eight  were  still  doing  so  six  weeks 
after  recovery. 

"Kayser,  tracing  outbreaks  to  their  sources,  found 
a  boy  of  twelve  years,  a  member  of  a  milkman's  fam- 


134    THE  HOUSE  FLY— DISEASE  CARRIER 

ily,  to  be  a  chronic  carrier  and  the  probable  source  of 
infection  in  a  number  of  cases.  Another  outbreak  in 
which  seventeen  persons  were  seized  (two  deaths)  was 
traced  to  a  woman  who  had  no  typhoid  history  but 
was  excreting*  the  specific  bacilli.  She  was  employed 
in  the  dairy  from  which  the  persons  seized  had  obtained 
their  milk.  Of  260  cases  of  typhoid  fever  investigated, 
sixty  were  traced  to  infected  milk.  Among  the  sixty 
victims  were  thirty  maids  and  kitchen  girls,  twelve 
bakers  and  forty-four  persons  engaged  more  or  less  in 
kitchen  work.  In  all,  twenty-eight  cases  were  traced 
directly  to  apparently  healthy  typhoid  carriers. 

"Minelli  examined  250  prisoners  who  had  not  been 
in  contact  with  typhoid  cases,  and  found  but  one  who 
had  the  specific  organism  constantly  in  the  feces.  The 
agglutinative  test  was  positive. 

"Etienne  and  Thiry  report  the  case  of  a  man,  sixty- 
four  years  of  age,  who,  after  four  years  in  a  hospital, 
under  treatment  for  tabes  and  hemiplegia,  had  two  at- 
tacks of  jaundice,  and  on  examination  was  found  to  be 
excreting  typhoid  bacilli  in  the  feces. 

"A  series  of  twenty-six  cases  of  the  disease  in  fifteen 
families  of  a  village  in  Lorraine  is  described  by  Seige, 
who  states  that  diligent  investigation  by  the  district 
physician,  the  village  authorities  and  the  Bacteriological 
Institute  of  Saarlouis  placed  the  responsibility  upon  a 
woman  who  was  a  chronic  typhoid  carrier. 

"An  interesting  case  of  infection  from  direct  contact 
is  reported  by  Dr.  H.  MacKenzie  and  by  Mr.  W.  H. 
Battle.  More  than  two  years  after  a  severe  attack  of 


CARRIAGE  OF  DISEASE  135 

typhoid  fever,  a  man  had  an  attack  of  femoral  osteo- 
myelitis, caused  by  B.  typhosus.  After  operation  the 
patient  was  discharged,  but  some  time  afterwards  a 
sinus  formed,  the  purulent  discharge  from  which  con- 
tained typhoid  bacilli.  The  patient's  wife  had  not  been 
in  contact  with  any  other  case,  but  frequently  removed 
and  burned  the  dressings.  After  a  time  she  fell  sick 
with  typhoid  fever,  and  died. 

"In  a  letter  to  the  writer,  under  date  of  April  3,  1907, 
in  response  to  a  request  for  information  concerning  a 
woman  described  in  the  press  as  a  'typhoid  factory'  and 
held  under  detention  by  the  Department  of  Health  of 
the  city  of  New  York,  Dr.  Walter  Bensel  says :  The 
woman  of  whom  you  write  has  given  a  history  of  a 
probable  mild  attack  of  typhoid  fever  about  six  years 
ago.  Since  that  time  there  have  been  undoubtedly 
twenty-eight  cases  of  typhoid  fever  in  the  families  in 
which  she  worked.  The  number  of  cases  occurring 
in  a  family  within  a  few  weeks  of  her  advent  varied 
from  one  or  two  up  to  six  out  of  seven  members.  The 
evidence  seemed  so  strong  that  she  was  a  carrier  of 
typhoid  fever  that  she  was  removed  to  Reception  Hos- 
pital by  force.  Examinations  of  her  feces  and  urine 
were  made,  and  the  typhoid  bacilli  found  in  her  feces 
confirmed  positively  our  suspicions  with  regard  to  the 
possibility  of  her  conveying  typhoid  fever.'  " 

Maj.  J.  C.  Morgan  and  Capt.  D.  Harvey,  Royal 
Army  Medical  Corps  ( 1909),  give  an  account  of  inves- 
tigations which  they  had  made  on  the  viability  of  the 
typhoid  bacillus  as  excreted  under  natural  conditions 


136    THE  HOUSE  FLY— DISEASE  CARRIER 

by  the  chronic  carrier.  As  it  happens,  they  had  several 
cases  of  chronic  carriers  under  observation.  In  their 
first  experiment,  typhoid  bacilli  were  recovered  from 
polluted  soil  six  hours  after  pollution,  but  thirty  hours 
after  none  could  be  recovered.  In  a  second  experiment, 
bacilli  were  recovered  five  and  one-half  hours  from 
soil  pollution.  In  a  third  experiment,  bacilli  were  re- 
covered five  hours  after  pollution,  and  again  thirty 
hours  after  pollution  of  the  soil;  none  later.  In  a 
fourth  experiment,  bacilli  were  recovered  twenty-four 
hours  after  contamination. 

The  sixth  and  seventh  experiments  were  made  with 
toweling,  to  indicate  the  viability  of  the  typhoid  bacillus 
on  cotton  fabrics.  A  piece  of  toweling  was  soaked  in  a 
sample  of  urine  which  was  found  to  contain  50,000 
bacilli  per  cc.  It  was  then  cut  into  pieces  and  put  into 
petri  dishes,  with  the  result  that  bacilli  were  found 
upon  some  of  the  pieces  up  to  and  including  the  fourth 
day  after  pollution,  where  the  pieces  had  been  exposed 
to  daylight.  Pieces  kept  in  the  dark  were  found  to  be 
infested  with  living  bacilli  up  to  and  including  the 
eleventh  day. 

In  another  experiment,  one  of  the  carriers  voided 
his  excrement  in  a  dry-earth  latrine,  with  the  result 
that  it  was  found  that,  under  the  conditions  of  a  dry- 
earth  closet  and  of  dry-earth  methods  of  disposing  of 
excreta,  typhoid  bacilli  can  readily  be  recovered  up 
to  a  week,  and  can  exist  in  the  interior  of  a  dry  fecal 
mass  up  to  eighteen  days.  This  indicates,  say  the 
writers,  how  easily  the  infection  could  be  conveyed 


CARRIAGE  OF  DISEASE  137 

by  flies  from  such  material  when  left  exposed  in  a 
latrine  pan. 

Another  experiment,  with  a  woolen  blanket  smeared 
with  a  fresh  sample  of  feces  from  a  carrier  and  doubled 
so  that  the  smear  was  outside,  gave  the  result  that  the 
bacillus  was  recovered  at  every  examination  up  to  and 
including  the  fortieth  day.  In  this  experiment  the 
sample  used  was  a  liquid  stool,  the  result  of  a  saline 
aperient,  and  portions  of  the  blanket  fiber  were 
pulled  out  from  the  soiled  portion  and  used  for  the 
experiment. 

The  latest  contribution  to  the  subject  at  this  time 
of  writing  is  Dr.  J.  C.  G.  Ledingham's  report  (1910). 
In  an  introduction  to  this  report,  Dr.  Theodore  Wilson 
states  that  the  difficulty  of  dealing  with  carriers  is  very 
great  indeed,  since  they  may  harbor  the  infection  for 
long  periods  and  it  is  extremely  difficult  to  free  them 
from  it.  It  is  most  important,  however,  that  all  possi- 
ble efforts  should  be  made  to  detect  carriers  and  to 
endeavor  to  secure  on  their  part  those  precautions  of 
strict  personal  cleanliness  and  of  disposal  of  dejecta 
which  will  minimize  the  risk  of  infecting  other  peo- 
ple. Furthermore,  Doctor  Thompson  points  out  that 
it  is  equally  important  that  an  attempt  should  be 
made  to  prevent  such  carriers  from  taking  any  part 
in  the  milk  trade  or  in  the  preparation  or  handling 
of  food. 

An  excellent  review  of  Dr.  Ledingham's  report  by 
Dr.  R.  M.  Grimm  will  be  found  in  Public  Health  Re- 
ports xxvi,  No.  4,  March  17,  1911. 


138    THE  HOUSE  FLY— DISEASE  CARRIER 

Influence  of  Flies  in  the  Carriage  of  Typhoid  in  Cities 

Much  of  what  we  have  just  written  refers  to  the 
carriage  of  typhoid  by  flies  in  encampments  of  troops 
and,  in  such  facts  as  we  have  given  about  the  Spanish- 
American  War  and  the  Boer  War,  to  their  effective 
carriage  in  temporary  camps.  We  have  equally  shown 
their  influence,  however,  at  more  or  less  permanent 
army  posts  and  the  certainty  of  the  inference  under 
these  conditions  is  acknowledged  by  practically  every 
one.  And  the  same  free  acknowledgment  must  be 
made  in  the  case  of  any  emergency  which  calls  together 
for  temporary  purposes  large  bodies  of  men,  engaged 
on  great  public  works,  for  example,  as  the  Panama 
Canal  or  the  construction  of  great  reservoirs,  or  in 
mining  camps.  Any  slight  lack  of  care  in  the  disposal 
of  excreta  under  such  conditions  almost  invariably 
brings  about  an  outbreak  of  typhoid,  and  most  often 
by  the  carriage  of  the  causative  organism  by  flies.  But 
does  the  same  thing  hold  for  cities?  The  opinion  of 
a  certain  class  of  conservative  medical  men  on  this 
point  is  well  expressed  in  a  recent  editorial  in  the  Jour- 
nal of  the  American  Medical  Association,  as  follows: 

"It  is  sometimes  easier  to  implant  a  new  idea  in  the 
human  mind  than  to  extract  it  or  modify  it  when  it 
has  once  taken  firm  root.  The  notion  that  bad  smells 
from  faulty  sewers  give  rise  to  specific  infections,  such 
as  diphtheria  and  typhoid  fever,  or  that  piles  of  gar- 
bage 'breed  disease/  are  cases  in  point.  In  the  public 
mind,  methods  of  garbage  disposal  and  elaborate 


CARRIAGE  OF  DISEASE  139 

plumbing  ordinances  often  loom  large  as  the  chief 
weapons  of  combating  disease.  Too  often  attention  is 
diverted  from  really  significant  and  tangible  dangers 
to  health  by  the  cry  that  the  garbage  dump  or  the  sew- 
age manhole  is  emitting  vile  odors.  It  is  of  course 
well  known  to  physicians  that  there  is  no  evidence  that 
disease  can  be  spread  by  odors,  although  foul  air  may 
possibly  impair  health  and  render  the  body  less  re- 
sistant to  disease. 

'  "Many  sanitarians  are  beginning  to  fear  that  a  sim- 
ilar misapplication  or  misunderstanding  of  the  relation 
of  the  house  fly  to  typhoid  fever  is  coming  about.  No 
one  questions  that  the  house  fly  is  an  unmitigated  nui- 
sance. Neither  is  there  any  doubt  that  under  certain 
conditions,  such  as  prevail  in  military  or  mining  camps 
or  on  many  a  country  farm,  or  even  in  cities  that  allow 
the  crude  type  of  privy,  the  house  fly  is  an  exceedingly 
important  agent  in  the  transmission  of  infection.  This 
has  been  abundantly  proved.  There  is  observable,  how- 
ever, a  tendency  to  assume  a  connection  much  wider 
than  this  and  to  attribute  to  fly  infection  a  portion, 
sometimes  the  major  portion,  of  the  typhoid  fever  oc- 
curring in  large  and  well-sewered  cities. 

"Several  instances  of  this  misguided  enthusiasm  have 
come  to  notice  within  the  last  few  months.  It  need 
hardly  be  pointed  out  that  the  house  fly,  no  matter  how 
disgusting  its  origin  or  habits,  cannot  convey  the  spe- 
cific germ  of  typhoid  fever  to  any  food  substance  un- 
less it  has  access  both  to  food  substances  and  to  typhoid 
germ.  Those  amateur  investigators  who  assume  that 


140    THE  HOUSE  FLY— DISEASE  CARRIER 

they  have  discovered  the  origin  of  a  typhoid  epidemic 
if  they  observe  a  few  piles  of  horse  manure  in  the 
alleys  of  a  city  take  a  wide  leap  over  logical  difficulties. 
Their  mode  of  reasoning  seems  to  be  this :  Flies  can 
breed  in  horse  dung,  flies  can  convey  typhoid  fever, 
therefore  flies  bred  in  these  dung  heaps  have  caused  or 
are  about  to  cause  typhoid  fever.  One  other  essential 
condition,  namely,  the  existence  of  infected  material 
to  which  the  flies  have  access,  is  left  out  of  account  in 
such  hasty  judgments. 

^"As  a  matter  of  fact,  grave  as  is  the  danger  of  fly 
transmission  of  typhoid  under  rural  conditions,  it  does 
not  seem  to  be  an  important  factor  in  the  production 
of  urban  typhoid.  As  is  well  known,  the  intensive 
study  of  typhoid  fever  in  Washington,  D.  C,  which 
extended  over  several  years,  yielded  no  evidence  that 
fly  transmission  had  any  noteworthy  share  in  typhoid 
fever  causation  in  that  city. 

"One  of  the  most  experienced  American  health  of- 
ficers has  taken  a  decided  stand  on  this  question  in  a 
book  recently  published.*  While  recognizing  the  de- 
sirability of  treating  garbage  in  such  a  way  as  to  pre- 
vent a  nuisance,  and  admitting  the  possibility  of  fly- 
borne  infection  where  open  privy  vaults  exist,  he  de- 
clares very  plainly  that  'there  is  no  evidence  that  in 
the  average  city  the  house  fly  is  a  factor  of  great  mo- 
ment in  the  dissemination  of  disease.'  V There  can  be 
no  doubt  that  in  any  reasonably  clean  and  well- 

*Chapin,  Charles  V. :  Sources  and  Modes  of  Infection.  New 
York.  1910. 


CARRIAGE  OF  DISEASE  141 

sewered  city  the  cases  of  typhoid  infection  due  to 
direct  fly  transmission  are  relatively  very  few  com- 
pared with  the  number  due  to  water,  to  milk  and  to 
contact  (including  contact  with  carriers).  As  one 
writer  has  said,  in  discussing  this  question,  'We 
need  more  scientific  knowledge  and  less  repetitious 
babble  of  sentiment  in  dealing  with  flies  or  any  other 


nuisance/ 


Such  ideas  as  this  are  likely  to  do  harm.  From 
every  point  of  view  it  is  desirable  to  rid  communities 
from  flies,  and  the  only  danger  of  over-emphasizing  the 
importance  of  the  typhoid  fly  in  its  relation  to  typhoid 
fever  is  that  it  may  be  accepted  as  the  principal  cause 
of  the  spread  of  the  disease  in  certain  cases  where  care- 
ful investigation  would  indicate  other  and  perhaps  eas- 
ily controllable  causes.  Therefore,  while  we  are  in- 
clined to  agree  with  the  writer  of  the  editorial  that 
statements  should  be  cautious  to  a  reasonable  extent, 
the  general  tone  of  the  editorial  undoubtedly  far  too 
greatly  minimizes  the  importance  of  flies  from  the  dis- 
ease point  of  view  in  modern  cities. 

Reference  is  made  to  "any  reasonably  clean  and  well- 
sewered  city."  The  city  of  Washington  has  the  repu- 
tation of  being  perhaps  the  cleanest  and  best-sewered 
city  in  the  United  States,  and  yet  it  is  possible  any 
summer  morning  to  find  human  dejecta  in  alleyways 
and  vacant  lots  deposited  there  over  night  by  irrespon- 
sible persons,  and  in  the  light  of  day  swarming  with 
flies.  In  the  poor  quarters  of  the  city  uncared-for  chil- 
dren of  the  indigent  ease  themselves  almost  wherever 


142    THE  HOUSE  FLY— DISEASE  CARRIER 

they  happen  to  be.*  The  writer  has  shown  that  the 
typhoid  fly  oviposits  upon  such  individual  dejecta  and 
that  its  larvse  successfully  breed  in  them,  and  that  the 
adult  flies  of  the  next  generation  issue  from  them  un- 
der the  ordinary  summer  moisture  conditions  that  pre- 
vail in  Washington. f  With  the  now  well-known  per- 
centage of  chronic  typhoid  carriers  (from  three  to  four 
per  cent.)  and  with  the  hundreds  of  cases  of  typhoid 
that  have  occurred  annually  in  the  city  of  Washington 
during  the  past  ten  years,  and  with  the  existence  as  ac- 
tually observed  of  such  loose  and  ill-placed  dejecta, 
and  with  flies  feeding  upon  them  and  breeding  in  them 
within  short  distances  from  unprotected  kitchens  and 
pantries,  to  say  nothing  of  markets  and  food  shops, 
how  is  it  possible  that  flies  should  be  factors  of  no  great 
moment?  Surely  there  must  be  scores  of  typhoid  car- 
riers living  in  Washington  to-day. 

Moreover,  there  still  exists  in  portions  of  even  the 
cleanly  city  of  Washington  the  uncared-for  box-privy 
nuisance.  The  judgment  in  this  case  is  not  hasty.  It 

This  occurs  in  every  city.  Newstead  in  his  Liverpool  (Eng- 
land) report  writes:  "In  the  course  of  my  investigations,  more 
especially  on  hot  days,  numbers  of  house  flies  were  seen  hovering 
over  or  feeding  on  such  matter  [human  droppings].  The  feces 
were  generally  those  of  children,  and  were  lying,  as  a  rule,  a  few 
feet  from  the  doorways,  in  the  courts  or  in  the  passages  behind 
the  houses.  In  one  instance  no  less  than  five  patches  of  human 
excreta  were  lying  in  one  court,  and  all  of  them  were  attended 
by  house  flies." 

fThe  exact  records  of  these  experiments  and  rearings  will  be 
found  in  the  writer's  1900  paper.  The  especial  cases  in  point  are 
mentioned  on  p.  572,  as  many  as  thirty-one  house  flies  being 
reared  from  a  single  dropping  of  a  child.  We  have  elsewhere 
mentioned  Major  Faichnie's  record  of  the  rearing  of  500  flies 
from  a  single  dropping. 


CARRIAGE  OF  DISEASE  143 

may  be  difficult  to  prove  directly  and  to  the  laboratory 
man  that  any  certain  percentage  of  typhoid  cases  are 
caused  in  this  way,  but  how  much  more  difficult  will 
it  be  to  prove  that  they  are  not?  And  is  not  a  great 
preponderance  of  such  evidence  as  we  have  in  favor 
of  the  conclusion  that  house  flies  are  great  dangers  even 
in  cities  as  well  cared  for  as  the  best  of  our  American 
cities  ? 

As  to  the  "repetitious  babble  of  sentiment  in  deal- 
ing with  flies/'  is  it  not  a  mistake  to  apply  such  words 
to  a  conscientious  effort  to  warn  the  public  of  a  danger 
which  surely  exists  under  certain  conditions  and  most 
probably  exists  in  all? 

It  was  stated  in  the  editorial  which  we  are  consid- 
ering that  the  intensive  study  of  typhoid  fever  in  Wash- 
ington, D.  C.,  which  extended  over  several  years  yielded 
no  evidence  that  fly  transmission  had  any  noteworthy 
share  in  typhoid  causation  in  the  city.  This  statement 
was  based  largely  upon  the  fact  that  the  fever  for  the 
most  part  was  absent  or  rare  in  portions  of  the  city 
where  the  box-privy  nuisance  still  exists  (and  it  should 
be  stated  that  the  health  officer  has  every  one  of  these 
nuisances  carefully  marked  on  a  map)  and  that  an  ef- 
fort made  during  the  summer  of  1908  to  ascertain 
whether  there  was  any  relation  between  the  curve  of 
typhoid  increase  and  the  curve  of  fly  increase  resulted 
in  apparent  failure. 

The  effort  was  undertaken  by  the  Bureau  of  En- 
tomology of  the  U.  S.  Department  of  Agriculture  in 
co-operation  with  the  Public  Health  and  Marine-Hos- 


144    THE  HOUSE  FLY— DISEASE  CARRIER 

pital  Service.  The  fly  gatherings  were  begun  about 
June  1 9th  and  continued  to  October  iQth,  having  cov- 
ered a  period  of  four  of  the  hottest  months  in  the  sea- 
son and  those  in  which  flies  are  most  troublesome.  The 
method  used  was  to  supply  such  of  the  members  of  the 
Bureau  force  as  lived  in  distinct  and  separate  sections 
of  the  city  with  a  quantity  of  sticky  fly  paper  with  in- 
structions to  expose  a  sheet  every  other  day  for  a 
period  of  forty-eight  hours.  The  sheets  were  then  re- 
turned to  the  Bureau  and  the  flies  carefully  counted 
and  recorded  upon  specially  prepared  cards  bearing  ad- 
dress and  date  of  each  exposure,  together  with  such 
data  as  could  be  secured  concerning  the  conditions  of 
nearby  stables  and  manure  heaps.  Certain  parts  of  the 
city,  among  the  slums  and  along  the  water  front,  were 
not  reached  by  the  regular  employes  of  the  Bureau, 
but,  that  these  sections  might  be  represented  in  the  re- 
port, two  assistants  were  detailed  for  the  purpose  and 
made  regular  rounds  on  bicycles,  collecting  fly-laden 
sheets  and  leaving  fresh  paper  three  times  a  week.  Sun- 
day, of  course,  was  a  day  of  rest,  and  this  fact  inter- 
fered to  some  extent  with  the  counts,  since  in  case  of 
papers  exposed  in  meat  shops  and  restaurants  flies  were 
usually  so  plentiful  that  the  maximum  catching  ca- 
pacity of  the  paper  was  reached  within  forty-eight 
hours. 

Sixty-two  stations  were  located  throughout  the  city. 
At  the  end  of  the  season  the  results  were  tabulated  and 
the  curve  of  increase  was  plotted.  At  the  same  time 
the  Public  Health  and  Marine-Hospital  Service  had 


CARRIAGE  OF  DISEASE  145 

been  plotting  the  curve  of  typhoid  prevalence,  and  on 
comparison  it  was  found  impossible  to  derive  any  dis- 
tinct connection  between  the  two  curves — such  connec- 
tion as  would  be  suggestive  of  cause  and  effect. 

During  the  summer  of  1909  a  series  of  investigations 
of  a  very  similar  character  was  carried  on  in  Provi- 
dence, R.  L,  by  Prof.  G.  F.  Sykes  (1910),  of  Brown 
University.  The  conclusions  reached  by  him  were  as 
follows:  (i)  Fly  nuisance  is  local.  (2)  Geographic 
distribution  of  pestiferous  flies  is  determined  by  local 
sanitary  conditions.  (3)  The  seasonal  distribution  is 
conditioned  by  meteorological  influences  (temperature 
and  sunshine).  (4)  Over  ninety-nine  per  cent,  of  the 
flies  caught  were  Musca  domestica,  the  remaining  frac- 
tional per  cent,  being  Lucilia  casar.  (5)  The  plotted 
curve  for  typhoid  cases  did  not  show  a  close  relation 
to  the  fly  curve,  but  did  show  a  close  parallel  to  the 
temperature  curve.  (6)  The  high-water  mark  for 
deaths  from  diarrhea  antedated  that  for  the  fly  season 
by  fully  three  weeks,  and  followed  from  one  to  two 
weeks  after  a  noticeable  rise  in  temperature..  (7)  The 
geographic  distribution  of  typhoid  cases  over  the  city 
was  largely  independent  of  areas  known  as  "unsani- 
tary" and  as  "fly  centers." 

It  is  to  be  mentioned  that  the  flies  caught  by  Pro- 
fessor Sykes  were  collected  in  three  kitchens,  the  Wash- 
ington observations  covering  sixty-two  stations. 

It  is  possible  that  Doctor  Chapin,  of  Providence,  the 
writer  referred  to  in  the  editorial  under  consideration, 
was  confirmed  in  his  opinion  by  the  result  of  Professor 


146    THE  HOUSE  FLY— DISEASE  CARRIER 

Sykes's  observations  in  his  own  home  city,  but  never- 
theless Doctor  Chapin  is  a  well-known  man  of  high 
scientific  standing  and  his  conclusions  must  be  viewed 
with  all  respect.  When  we  come  to  analyze  the  situa- 
tion, however,  it  becomes  at  once  apparent  that  in  cities 
the  correlation  or  non-correlation  of  the  curve  of  house 
fly  abundance  and  of  the  abundance  of  typhoid  has 
practically  no  effect  upon  our  conclusions  as  regards 
the  possible  transfer  of  the  disease  by  flies. 

Flies  are.  numerous  at  all  times  during  the  summer, 
and  wherever  excreta  carrying  virulent  germs  can  be 
reached  by  them  it  is  sure  to  be  covered  by  them— 
whether  in  early  June  or  in  October — and  the  chances 
are  almost  as  great  that  food  supplies  will  be  reached 
by  these  flies  whether  there  are  500  of  them  or  600  of 
them.  The  fact  that  typhoid  fever  does  not  develop 
in  localities  where  flies  are  most  numerous  does  not 
mean  that  it  is  not  carried  by  flies,  but  simply  means 
that  the  flies  in  that  locality  have  had  no  opportunity 
to  visit  substances  containing  virulent  germs.  A  cor- 
relation of  the  two  curves  in  question  has  been  found 
by  Doctor  Jackson  in  his  report  to  .the  Merchants'  As- 
sociation of  New  York,  and  it  has  been  found  by  Cap- 
tain Ainsworth  in  his  studies  of  the  house  fly  and 
enteric  fever  in  India,  by  Purdy  (1910)  in  New 
Zealand,  and  by  Osmond  (1909)  in  Cincinnati,  and 
where  it  is  coincident  it  may  serve  to  attract  the  atten- 
tion of  people  to  the  subject,  but  the  absence  of  the 
correlation  in  any  given  case  is  a  most  inconclusive  ar- 
gument. 


CARRIAGE  OF  DISEASE  147 

A  most  careful  and  thoroughly  scientific  study  of 
the  seasonal  prevalence  of  typhoid  has  been  made  by 
Sedgwick  and  Winslow  (1902).  Their  investigation 
included  an  examination  of  the  published  data  for  all 
countries.  They  conclude  that  the  increase  of  typhoid 
with  a  gradual  rise  in  the  mean  air  temperature  is  so 
widespread  and  significant  as  to  indicate  an  undoubted 
relationship.  There  is  no  doubt  that  a  similar  rise  of 
temperature  hastens  the  rapidity  of  breeding  of  the 
house  fly  until  at  the  culmination  of  the  heated  term 
they  are  present  in  countless  numbers,  as  we  have  seen. 
This  fact  was  fully  appreciated  by  Sedgwick  and  Win- 
slow,  who  in  their  conclusions  use  the  following  words : 

"Of  the  three  great  intermediaries  of  typhoid  trans- 
mission, fingers,  food,  and  flies,  the  last  is  even  more 
significant  than  the  others  in  relation  to  seasonal  varia- 
tion. *•*..*  There  can  be  little  doubt  that  many  of 
the  so-called  'sporadic'  cases  of  typhoid  fever,  which 
are  so  difficult  for  the  sanitarian  to  explain,  are  con- 
ditioned by  the  passage  of  a  fly  from  an  infected  vault 
to  an  unprotected  table  or  an  open  larder.  The  relation 
of  this  factor  to  the  season  is  of  course  close  and  com- 
plete :  and  a  certain  amount  of  the  autumnal  excess  of 
fever  is  undoubtedly  traceable  to  the  presence  of  large 
numbers  of  flies  and  to  the  opportunities  for  their  per- 
nicious activity." 

The  real  explanation,  according  to  these  authors,  of 
the  seasonal  variations  of  typhoid  fever  is  a  direct  ef- 
fect of  temperature  upon  the  persistence  in  nature  of 
germs  which  proceed  from  previous  victims  of  disease. 


148    THE  HOUSE  FLY— DISEASE  CARRIER 

This,  of  course,  means  that  there  are  more  typhoid 
germs  in  late  summer  and  autumn,  and  as  there  are 
at  the  same  time  more  flies  to  carry  them,  the  necessity 
of  destroying  flies,  especially  in  the  early  summer,  is 
emphasized  by  this  conclusion. 

Other  Points 

It  may  be  that  enough  has  been  said  on  the  subject 
of  the  carriage  of  typhoid  by  flies,  but  there  is  a  great 
deal  of  evidence  that  has  not  been  touched  upon  at  all. 
Dr.  J.  W.  Palmer  of  Ailey,  Ga.,  for  example,  who  has 
had  much  experience  with  typhoid  in  a  region  for  the 
most  part  agricultural,  although  in  a  rich  part  of  the 
State  of  Georgia,  informed  the  writer  in  the  autumn 
of  1910  that  in  order  to  emphasize  the  importance  of 
flies  in  the  distribution  of  this  disease  and  to  carry 
conviction  to  his  patients  as  to  the  necessity  of  screen- 
ing their  houses  and  avoiding  flies,  he  promises  to  treat 
without  charge  all  cases  of  typhoid  fever  that  develop 
in  houses  well  protected  from  flies,  and  states  that  he 
has  never  had  a  case  develop  in  such  a  house. 

In  the  Transactions  of  the  Medical  Association  of 
Georgia  for  1910,  an  article  by  Doctor  Palmer  is  pub- 
lished on  pages  149  to  157.  In  this  paper  he  states 
that  he  estimates  that  ninety-five  per  cent,  of  the  ty- 
phoid fever  in  rural  districts  may  be  laid  to  the  typhoid 
fly.  He  states  that  during  the  past  typhoid  season  he 
treated  fever  in  several  families,  and  especially  noticed 
that  in  the  families  which  controlled  the  flies  as  di- 
rected by  him  no  new  cases  developed,  while  families 


CARRIAGE  OF  DISEASE  149 

which  did  not  control  the  flies  had  anywhere  from  one 
to  four  cases  in  each  family.  He  points  out  that  in  one 
year  typhoid  causes  more  deaths  than  yellow  fever  in 
fifty  years. 

The  Georgia  State  Medical  Association  as  early  as 
April,  1909,  appointed  an  executive  committee  of  five, 
known  as  the  "Fly  Committee,"  and  this  committee  ap- 
pointed a  sub-committee  consisting  of  one  member  from 
each  county,  whose  duty  it  has  been  to  give  public 
lectures  on  the  dangers  of  the  common  house  fly,  espe- 
cially in  every  public  school  in  their  respective  counties. 

Capt.  R.  B.  Ainsworth,  of  the  Royal  Army  Medical 
Corps  (1909),  gives  an  admirable  summary  of  impor- 
tant observations  in  India,  from  which  he  concludes  that 
flies  are  of  the  greatest  importance.  He  refers  to  much 
the  same  general  tone  of  the  medical  profession  as  that 
indicated  in  the  quoted  editorial  in  our  previous  sec- 
tion. He  writes,  "Notwithstanding  the  fact  that  much 
has  been  written  of  late  regarding  the  life  history  and 
habits  of  the  common  house  fly,  and  many  suggestions 
made  relative  to  its  possibilities  as  a  disease  carrier,  it 
is  to  be  feared  that  the  general  tone  of  the  medical  pro- 
fession with  regard  to  the  question  is  apathetic  if  not 
actually  antagonistic.  The  latter  is  distinctly  in  evi- 
dence in  a  rider  to  the  recent  reports  of  the  Simla 
Enteric  Fever  Committee,  added  by  some  members 
thereof,  though  why  they  should  dissent  so  emphat- 
ically in  the  face  of  so  rapidly  accumulating  proof  is 
hard  to  understand." 

After  his  summary  of  the  whole  situation,  Captain 


150    THE  HOUSE  FLY— DISEASE  CARRIER 

Ainsworth  concludes,  "It  seems  to  me  that  enteric  pre- 
vention naturally  groups  itself  under  five  headings, 
namely,  ( i )  Isolation  of  the  human  carrier,  failing 
(2)  elimination  of  the  bacillus  by  means  of  some  drug 
as  yet  undiscovered;  (3)  rendering  excreta  innoxious 
by  disinfection,  water  carriage,  and  similar  sanitary 
measures;  (4)  the  establishment  of  immunity;  and  (5) 
the  destruction  of  the  go-between,  to  wit,  the  fly/' 

CHOLERA 

One  of  the  earliest  accurate  scientific  studies  of  the 
agency  of  insects  in  the  transfer  of  human  diseases  was 
with  regard  to  flies  as  spreaders  of  cholera.  The  be- 
lief in  this  agency  long  preceded  its  actual  proof.  Dr. 
George  E.  Nicholas  (1873)  is  quoted  by  Nuttall  as 
writing  as  follows  regarding  the  cholera  prevailing  at 
Malta  in  1849: 

"My  first  impression  of  the  possibility  of  the  trans- 
fer of  the  disease  by  flies  was  derived  from  the  observa- 
tion of  the  manner  in  which  these  voracious  creatures, 
present  in  great  numbers,  and  having  equal  access  to 
the  dejections  and  food  of  the  patients,  gorged  them- 
selves indiscriminately  and  then  disgorged  themselves 
on  the  food  and  drinking  utensils.  In  1850  the  'Superb,' 
in  common  with  the  rest  of  the  Mediterranean  squad- 
ron, was  at  sea  for  nearly  six  months;  during  the 
greater  part  of  the  time  she  had  cholera  on  board.  On 
putting  to  sea  the  flies  were  in  great  force;  but  after 
a  time  the  flies  gradually  disappeared,  and  the  epidemic 
slowly  subsided.  On  going  into  Malta  harbor,  but 


CARRIAGE  OF  DISEASE  151 

without  communicating  with  the  shore,  the  flies  re- 
turned in  greater  force,  and  the  cholera  also  with  in- 
creased violence.  After  more  cruising  at  sea,  the  flies 
disappeared  gradually  with  the  subsidence  of  the  dis- 
ease." 

C.  Flugge  is  said  by  Nuttall  and  Jepson  to  have  ex- 
pressed his  belief  in  1886  that  flies  may  infect  the  food 
in  cholera  times.  Their  numbers  vary  extraordinarily 
at  times  and  in  certain  places.  They  must  play  an  im- 
portant part,  especially  when  they  are  numerous.  He 
drew  attention  to  the  fact  that  the  worst  cholera  months 
are  those  in  which  insects  abound. 

Dr.  J.  Tsuzuki,  of  the  Japanese  Army  Medical  Ser- 
vice, writing  in  1904  upon  his  researches  during  the 
cholera  epidemic  in  North  China  in  1902,  stated  that 
flies  in  China  are  a  terrible  infliction  to  the  stranger, 
and  that  if  they  are  capable  of  carrying  the  cholera 
germ  they  must  play  an  important  part  in  the  spread 
of  the  disease.  He  captured  flies  in  Tientsin  in  houses 
in  which  there  were  cholera  patients,  and  succeeded  in 
isolating  cholera  vibrios  from  them.  He  also  placed 
flies  in  a  cage  with  a  cholera  culture  and  a  dish  con- 
taining sterilized  agar,  with  the  result  that  cholera  col- 
onies developed  upon  the  agar. 

But  this  was  not  the  first  definite  and  conclusive  ex- 
periment in  this  regard,  since  Nuttall  and  Jepson  point 
out  that  something  had  been  done  in  1886  by  two 
Italian  physicians  in  Bologna,  and  that  Sawtchenko,  of 
St.  Petersburg,  in  1892,  found  that  when  flies  had  fed 
for  some  time  on  a  cholera  culture  almost  no  other 


152    THE  HOUSE  FLY— DISEASE  CARRIER 

bacteria  could  be  isolated  from  their  dejections.  In 
the  same  year  M.  Simmonds  studied  the  flies  in  a  hos- 
pital in  Hamburg,  especially  those  present  in  the  post- 
mortem room,  where  many  bodies  and  intestines  of 
persons  dead  of  cholera  were  lying.  He  was  able  to 
isolate  cholera  vibrios  from  the  first  fly  caught.  He 
had  the  room  cleaned  at  once,  and  after  this  was  unable 
to  obtain  cholera  germs  from  flies  caught.  He  found 
that  healthy,  active  cultures  could  be  made  from  flies 
for  an  hour  and  a  half  after  they  had  visited  infected 
material. 

Much  the  same  work  was  done  in  that  year  and  sub- 
sequent years  by  Uffelmann,  and  in  1905  Chantemesse 
succeeded  in  isolating  cholera  vibrios  from  the  feet  of 
flies  seventeen  hours  after  they  had  been  contaminated. 
In  1908  Ganon  stated  that  flies  can  transmit  infection 
for  at  least  twenty-four  hours  after  a  meal  of  infected 
material,  and  showed  that  that  period  is  sufficient  to 
allow  them  to  be  carried  for  a  long  distance  in  railway 
trains.  Nuttall  and  Jepson  point  out  that  the  various 
experiments  made  during  this  period  gain  in  value  from 
the  fact  that  the  investigators  were  to  a  large  extent 
ignorant  of  the  work  done  by  others,  and  they  add  that 
a  number  of  authors,  without  contributing  any  personal 
evidence  on  the  subject,  express  their  conviction  that 
the  house  fly  carries  cholera.  They  consider  that  the 
body  of  evidence  which  they  present  as  to  the  part 
played  by  flies  in  the  dissemination  of  cholera  appears 
to  be  quite  convincing. 

An  interesting  and  important  piece  of  work  in  this 


CARRIAGE  OF  DISEASE  153 

direction  was  done  by  Surgeon  Major  R.  Macrae 
(1894),  the  civil  surgeon  of  Gaya,  India,  at  the  time 
of  an  outbreak  of  cholera  in  the  jail  at  that  place.  He 
had  in  the  case  of  the  jail  at  Gaya  a  definite  structure 
composed  of  eight  yards,  and  thus  his  observations  were 
condensed,  and  his  medical  authority  enabled  him  to 
control  the  situation  to  a  sufficient  extent  to  prove  his 
conclusions  to  his  satisfaction  and  practically  to  that 
of  every  one  else.  With  much  detail  he  gives  a  map 
of  the  jail  enclosures  and  a  description  of  them,  to- 
gether with  an  account  of  the  distribution  of  the  pris- 
oners. The  cholera  outbreak  was  under  his  charge  and 
thorough  examinations  were  made  of  all  of  the  possible 
means  of  spread.  The  water  supply  was  shown  to  be 
above  suspicion.  The  milk  was  of  excellent  quality  and 
the  food  as  well.  A  high  wall  separated  the  male  de- 
partment from  that  of  the  females  and  cut  off  the  fly 
infection;  no  cases  of  cholera  occurring  in  the  female 
side.  As  Macrae  states :  "It  was  observed  before  the 
epidemic  occurred  that  the  jail  was  infested  with  a 
plague  of  flies;  disinfectants  of  various  kinds  were 
used,  but  they  could  not  be  got  rid  of.  The  moist, 
steaming  weather  appeared  to  favor  their  development. 
They  were  present  in  swarms  when  the  disease  broke 
out,  and  it  was  an  observation  of  daily  occurrence  to 
see  them  settling  on  cholera  stools  wherever  possible. 
The  rest  can  be  imagined!  As  soon  as  feeding  time 
arrived  and  the  food  was  distributed  in  the  usual  way 
on  open  iron  plates  on  the  feeding  platforms,  there  was 
at  once  a  crowding  of  flies  towards  the  platforms,  and 


154    THE  HOUSE  FLY— DISEASE  CARRIER 

a  struggle  between  them  and  the  prisoners  for  the 
food.  An  active  prisoner  might  possibly  be  able  to 
protect  his  plate  from  contact  with  them;  but  many 
are  careless  and  do  not  seem  to  mind  much/'  Actual 
experiments  were  made  by  exposing  boiled  milk;  and 
that  exposed  on  the  male  side  became  infected  with  the 
cholera  germ.  In  conclusion,  Macrae  writes : 

"The  practical  lesson  the  experiments  teach  is,  that 
flies  should  be  looked  upon  in  the  light  of  poisonous 
agencies  of  the  worst  kind  during  cholera  epidemics, 
as  it  is  clear  that  if  they  find  access  to  poison  they  will 
carry  and  distribute  it,  and  every  possible  means  should 
be  taken  to  prevent  their  getting  into  contact  with  either 
food  or  drink  of  any  kind,  and  to  those  having  to  deal 
with  large  bodies  of  men  it  is  a  lesson  more  easily 
learnt  than  put  into  practice." 

Another  interesting  instance  of  a  somewhat  similar 
nature  is  cited  by  Nuttall  and  Jepson,  in  which  they 
state  that  W.  T.  Buchanan,  in  1897,  described  a  jail 
epidemic  which  occurred  at  Burdwan  in  June,  1896. 
This  was  also  the  case  of  a  prison.  Outside  of  the 
prison  there  were  some  huts  where  cholera  prevailed. 
It  is  said  that  a  strong  wind  blew  great  numbers  of 
flies  from  the  side  where  these  huts  were  into  the  prison 
enclosure,  where  they  settled  on  the  food  of  the  pris- 
onerss.  It  resulted  that  only  those  prisoners  who  were 
fed  at  the  jail  enclosure  nearest  the  huts  came  down 
with  cholera,  while  the  others  remained  healthy. 


CARRIAGE  OF  DISEASE  155 

DYSENTERY 

The  probability  of  the  carriage  of  dysentery  as  an 
intestinal  disease  has  been  suggested  by  several  writers 
and  especially  by  medical  officers  of  the  English  army 
in  India,  and  two  of  these  were  referred  to  by  Nuttall 
and  Jepson  in  1909,  but  at  that  time  these  authors  were 
obliged  to  state  that  there  was  no  direct  evidence  bear- 
ing upon  flies  in  relation  to  dysentery.  Since  the  publi- 
cation of  their  abstract  of  the  literature,  however,  an 
important  paper  has  been  published  by  Orton  and 
Dodge  (1910).  We  have  previously  referred  to  this 
paper  under  the  heading  "Substances  in  which  the  early 
life  is  passed." 

It  seems  that  during  1910  an  epidemic  of  136  cases 
of  bacillary  dysentery  occurred  in  the  Worcester  State 
Hospital  and  Doctor  Orton  found  that  the  epidemic 
had  spread  gradually.  It  was  not  characterized  by  a 
sudden  general  series  of  cases.  This,  of  course,  argued 
against  the  theory  of  a  water-supply  infection,  and  it 
also  argued  equally  well  against  milk  infection  and  in- 
fection from  raw  foodstuffs.  It  is  obvious  that  with 
infection  from  any  of  these  sources  a  large  number  of 
patients  would  have  become  ill  at  the  same  time.  House 
flies  were  unusually  abundant  in  the  hospital  in  spite 
of  screening,  and  these  were  considered  to  be  the  car- 
riers of  the  dysentery.  We  have  elsewhere  shown  that 
it  was  finally  discovered  that  the  unusual  number  of  the 
flies  was  due  to  certain  piles  of  spent  hops  and  barley 
malt  which  had  been  hauled  in  as  fertilizer  on  the 
grounds  near  the  buildings. 


156    THE  HOUSE  FLY— DISEASE  CARRIER 

The  case  reported  is  interesting  and  unusual  on  ac- 
count of  the  fact  that  the  hospital  in  question  is  a  hos- 
pital for  the  insane,  and  that  it  is  impossible  in  such 
an  institution  to  control  the  intestinal  discharges  of 
the  patients  and  confine  them  to  one  place.  In  the 
hospital  all  bedding  and  clothing  were  brought  for 
cleaning  to  the  laundry,  and  the  laundry  contained 
many  flies,  and  in  the  laundry  colonies  of  Bacillus 
prodigiosus  were  exposed  under  experimental  condi- 
tions. Subsequently  at  varying  interyals  flies  were 
caught  in  the  other  rooms  of  the  hospital,  and  upon 
test  from  a  large  number  of  them  cultures  of  the  Bacil- 
lus were  had. 

Doctor  Orton's  conclusion  as  published  is  that  flies 
were  entirely  responsible  for  the  epidemic.  It  is  rather 
a  pity  that  the  causative  organism  of  the  dysentery 
could  not  have  been  used  in  this  experiment,  but  that 
was  of  course  impossible  on  account  of  the  danger,  and 
it  is  altogether  probable  that  Doctor  Orton's  conclusions 
from  his  experiments  with  the  other  Bacillus  were  per- 
fectly correct. 

Dr.  C.  W.  Stiles  tells  the  writer  that  the  causative 
organism  of  amoebic  dysentery  sporulates  more  readily 
as  the  feces  dry.  Therefore  under  a  dry-privy  system 
this  disease  is  the  more  likely  to  be  carried  by  flies. 

DIARRHEA  IN  INFANTS 

Diarrhea  and  enteritis,  commonly  known  as  summer 
complaint,  cause  a  great  mortality  among  children  in 
the  United  States.  It  is  doubtful  whether  the  average 


CARRIAGE  OF  DISEASE  157 

person  begins  to  realize  the  full  extent  of  the  ravages 
of  this  disease,  and  indeed  of  the  mortality  rate  among 
young  children.  The  Census  Bureau  shows  that  in 
1908  nearly  one-fifth  of  the  deaths  in  the  registration 
area  of  the  United  States,  comprising  about  one-half 
of  the  population  of  the  country  as  a  whole,  were  of 
children  under  one  year,  and  that  the  deaths  of  children 
under  five  years  comprise  more  than  one-quarter  of  the 
whole  number  of  deaths.  Ratios  are  not  as  convincing 
or  as  strong  as  actual  figures,  so  that  we  may  say  in 
other  words  that  the  deaths  in  the  registration  area  in 
1908  amounted  to  691,574;  those  of  children  under  one 
year  to  136,452,  and  of  those  under  five  years  189,865. 
It  is  a  recognized  fact  that  the  general  death  rate  of 
the  country  is  largely  dependent  on  its  infant  mor- 
tality. 

The  number  of  deaths  among  children  becomes  even 
more  striking  when  we  consider  that  in  1908,  according 
to  the  census,  197.3  out  °f  every  1,000  under  one  year 
died,  while  274.5  out  of  every  1,000  under  five  years 
died.  It  is  clearly  shown  that  summer  complaint  is  the 
most  important  cause  of  infant  mortality.  Irving 
Fisher,  in  his  estimate  of  lives  that  could  be  saved, 
states  that  sixty  out  of  every  one  hundred  dying  from 
this  disease  could  have  been  saved.  The  actual  num- 
ber of  deaths  from  summer  complaint  in  1908  was  52,- 
213,  of  which  44,521  were  under  two  years. 

Of  course  there  is  no  way  of  showing  in  what  pro- 
portion of  these  cases  of  summer  complaint  the  house 
fly  was  instrumental,  but  under  conditions  that  exist 


158    THE  HOUSE  FLY— DISEASE  CARRIER 

practically  everywhere  in  midsummer,  both  as  to  the 
swarms  of  flies  and  the  lax  care  of  excreta  among 
small  children,  it  is  impossible  to  avoid  the  conclusion 
that  flies  bear  a  very  important  relation  to  the  number 
of  cases  and  therefore  to  the  number  of  deaths. 

Nuttall  and  Jepson  have  abstracted  a  number  of  pub- 
lished papers  on  this  subject,  with  the  following  re- 
sults : 

'The  relation  of  flies  to  the  spread  of  summer  diar- 
rhea has  aroused  special  interest  of  recent  years.  Eraser 
(1902),  referring  to  epidemic  diarrhea  in  Portsmouth, 
states  that  'on  visiting  the  houses  in  question  I  find 
that  in  all,  almost  without  exception,  the  occupants 
have  suffered  from  a  perfect  plague  of  flies.  They  told 
me  every  article  of  food  is  covered  at  once  with  flies. 
*  *  *  I  repeat  that  to  this,  and  this  alone,  I  at- 
tribute the  diarrhea  in  the  Goldsmith  Avenue  district.' 

"Nash  (1903,  p.  128)  pointed  out  that  there  were 
twenty-three  cases  of  the  disease  in  Southend-on-Sea  in 
1901,  whilst  there  were  none  in  the  summer  of  1902. 
M.  domestica  was  completely  absent  in  the  wet  summer 
of  1902,  but  appeared  in  September  of  the  same  year; 
coincident  therewith  there  occurred  thirteen  cases  of 
infantile  diarrhea.  Nash  (1904)  considers  that  M. 
domestica  is  the  chief  carrier  of  diarrhea-causing  bac- 
teria. 

"Newsholme  (1903,  p.  21)  has  expressed  the  opin- 
ion that  food  in  the  houses  of  the  poor  can  scarcely 
escape  fecal  infection.  The  sugar  used  in  sweetening 
milk  is  often  black  with  flies,  which  may  have  come 


CARRIAGE  OF  DISEASE  159 

from  a  neighboring-  dust-bin  or  manure  heap,  or  from 
the  liquid  stools  of  a  diarrheal  patient  in  a  neighboring 
house.  Flies  have  to  be  picked  out -of  the  half-empty 
can  of  condensed  milk  before  its  remaining  contents 
can  be  used  for  the  next  meal.'  Newsholme  considers 
the  greater  prevalence  of  diarrhea  among  infants  fed 
on  Nestle's  milk  as  due  to  the  fact  that  flies  are  more 
attracted  to  it  than  to  ordinary  cow's  milk  because  of 
its  sweetness. 

"Copeman  (1906,  p.  18),  in  a  report  to  the  Local 
Government  Board  dealing  with  epidemic  prevalence  of 
infantile  diarrhea  at  Wigan,  says :  'At  the  Miry  Lane 
Depot  there  is  always  stored  (awaiting  removal  by 
farmers)  an  enormous  amount  of  night-soil  mixed  with 
ashes  which,  in  hot  weather  especially,  is  not  only  ex- 
ceedingly offensive,  but  is  beset  by  myriads  of  house 
flies.  As  the  result  of  personal  enquiry  at  the  various 
houses  in  the  neighborhood  in  which,  during  the  year 
1905,  deaths  from  diarrhea  had  occurred,  I  learnt  that 
considerable  nuisance  from  the  foul  odors  was  apt  to 
be  experienced  during  the  prevalence  of  hot  weather, 
especially  with  the  wind  in  the  south  or  southwest,  i.  e., 
blowing  from  the  Depot  to  the  special  area,  so  much 
so  on  occasions  as  to  render  it  necessary  to  shut  all  the 
windows,  while  the  inhabitants  of  houses  nearest  the 
Corporation  Depot  stated  that  at  certain  times  of  the 
year  their  rooms  were  apt  to  be  invaded  by  a  veritable 
plague  of  flies,  which  swarmed  over  everything  of  an 
edible  nature  on  the  premises.  This  being  so,  it  would 
appear  not  improbable  that  these  flies,  some  of  which 


160    THE  HOUSE  FLY— DISEASE  CARRIER 

have  doubtless  had  opportunity  of  feeding  on  and  be- 
coming contaminated  with  excremental  material  of 
human  origin,  may  have  been  a  means  of  carrying  in- 
fected material  to  certain  foodstuffs,  such,  more  par- 
ticularly, as  milk  and  sugar,  and  so,  indirectly,  of 
bringing  about  infection  of  the  human  subject.' 

"Snell  (1906),  Medical  Officer  of  Health,  Coventry, 
is  stated  by  Ainsworth  (1909)  to  have  shown  that 
seventy  per  cent,  of  the  'cases  of  infantile  diarrhea  oc- 
curred in  the  northeast  part  of  his  district,  close  to  a 
large  collection  of  refuse  where  flies  swarmed.' 

"Sandilands  (1906,  p.  90)  considers  that  there  are 
'good  grounds  for  the  supposition  that  in  this  disease, 
which  in  some  respects  is  analogous  to  typhoid  fever 
and  cholera,  flies  may  be  carrying  agents  of  the  first 
importance.'  He  notes  that  the  meteorological  condi- 
tions which  influence  the  prevalence  of  diarrhea  'exer- 
cise a  precisely  similar  effect  upon  the  prevalence  of 
flies. 

The  immunity  of  well-to-do  infants  may  be  ex- 
plained partly  by  the  distance  that  separates  the  sick 
from  the  healthy  and  partly  by  the  small  number  of 
flies  in  their  neighborhood.  In  poorer  districts  six  or 
seven  babies  may  occupy  the  tenements  of  one  house 
with  a  common  yard  where  the  flies  congregate  and 
flit  in  and  out  of  the  open  windows,  themselves  con- 
veying infected  excrement  to  the  milk  of  healthy  in- 
fants, or  depositing  the  excrement  in  the  dust-bin, 
whence  it  may  again  be  conveyed  into  the  house  by 
other  flies.  Calm  weather  promotes  diarrhea,  and  high 


CARRIAGE  OF  DISEASE  161 

winds  are  unfavorable  to  the  spread  of  diarrhea  and  to 
the  active  migration  of  flies  alike.  Loose  soil  and  fis- 
sured rock,  containing  organic  filth  in  its  crevices,  favor 
the  spread  of  diarrhea  and  the  breeding  of  flies,  whilst 
solid  rock  is  unfavorable  to  both.'  (See  also  News- 
holme,  1906,  p.  145.) 

"Hamer  (1908),  who  has  studied  the  relation  of  fly 
prevalence  (Musca,  Homalomyia)  to  diarrhea  from  an 
epidemiological  point  of  view,  appears  to  be  somewhat 
sceptical  as  to  flies  being  active  agents  in  the  spread  of 
infection.  He  considers  that  the  increase  in  flies  and 
diarrhea  may  be  due  simply  to  a  coincidence. 

"Ainsworth  (1909,  p.  498)  has  studied  the  relation 
of  infantile  diarrhea  to  flies  in  Poona  and  Kirkee,  India, 
and  illustrates  the  relation  by  means  of  a  yearly  curve 
which  is  very  striking  as  affording  evidence  that  flies 
stand  in  causal  relationship  to  diarrhea. 

"All  authorities  agree  that  flies  rest  under  strong 
suspicion  of  serving  as  disseminators  of  diarrheal  in- 
fection." 

Jackson  (1907)  gives  the  results  of  numerous  ob- 
servations upon  the  relation  of  flies  to  intestinal  dis- 
eases (including  infant  diarrhea)  and  the  relation  of 
deaths  from  intestinal  diseases  in  New  York  City  to 
the  activity  and  prevalence  of  the  common  house  fly 
is  indicated  not  only  by  repeated  observations  but  also 
by  an  interesting  plotting  of  the  curve  of  abundance 
of  flies  in  comparison  with  the  plotted  curve  of  the 
abundance  of  deaths  from  intestinal  diseases,  indicat- 
ing that  the  greatest  number  of  flies  occurred  in  the 


162    THE  HOUSE  FLY— DISEASE  CARRIER 

weeks  ending  July  2?th  and  August  3d,  and  also  that 
the  deaths  from  intestinal  diseases  rose  above  the  nor- 
mal at  the  same  time  at  which  flies  became  prevalent, 
culminated  at  the  same  high  point,  and  fell  off  with  a 
slight  lag  at  the  time  of  the  gradual  falling  off  of  the 
prevalence  of  the  insects. 

TUBERCULOSIS 

The  typhoid  fly  also  possesses  importance  as  a  dis- 
seminator of  the  bacilli  of  tuberculosis.  We  have  seen 
on  an  earlier  page  the  method  by  which  the  adult  fly 
feeds  upon  sputa.  They  are  attracted  to  all  sputa  and 
feed  upon  them  with  avidity.  One  of  the  writer's  as- 
sistants (himself  a  tuberculous  patient)  more  than  ten 
years  ago  wrote  him  from  a  Colorado  resort  telling  of 
the  lax  care  of  the  sputa  of  the  consumptives,  and 
stating  that  he  had  seen  numbers  of  patients  sitting 
upon  a  veranda  and  occasionally  expectorating  over  the 
railing  upon  the  ground  where  numerous  flies  had  con- 
gregated and  were  feeding.  The  significant  part  of  the 
letter,  however,  was  the  statement  that  the  open  win- 
dows of  the  kitchen  were  not  many  feet  away  from  this 
particular  portion  of  the  veranda. 

It  is  not  difficult  to  understand  the  danger  of  the 
transfer  of  the  causative  organisms  of  the  diseases  of 
the  alimentary  tract  by  flies,  but  in  regard  to  tubercu- 
losis of  the  lungs,  it  should  be  stated  that  the  observa- 
tions of  Nicolas  and  Descas  (quoted  by  Cobb)  indi- 
cated that  fasting  dogs  fed  with  bouillon  containing 
quantities  of  bacilli  were  shortly  after  examined  and 


CARRIAGE  OF  DISEASE  163 

smears  were  taken  from  the  thoracic  duct  which  indi- 
cated tubercle  bacilli,  thus  showing  how  easily  these 
bacilli  can  enter  the  general  circulation. 

Dr.  Frederick  T.  Lord  (1904),  after  a  series  of  long 
and  careful  laboratory  investigations,  reached  the  fol- 
lowing conclusions: 

"i.  Flies  may  ingest  tubercular  sputum  and  excrete 
tubercle  bacilli,  the  virulence  of  which  may  last  for  at 
least  fifteen  days. 

"2.  The  danger  of  human  infection  from  tubercular 
fly-specks  is  by  the  ingestion  of  the  specks  on  food. 
Spontaneous  liberation  of  tubercle  bacilli  from  fly- 
specks  is  unlikely.  If  mechanically  disturbed,  infec- 
tion of  the  surrounding  air  may  occur. 

"As  a  corollary  to  these  conclusions,  it  is  suggested 
that— 

"3.  Tubercular  material  (sputum,  pus  from  dis- 
charging sinuses,  fecal  matter  from  patients  with  intes- 
tinal tuberculosis,  etc.)  should  be  carefully  protected 
from  flies,  lest  they  act  as  disseminators  of  the  tubercle 
bacilli. 

"4.  During  the  fly  season  greater  attention  should 
be  paid  to  the  screening  of  rooms  and  hospital  wards 
containing  patients  with  tuberculosis  and  laboratories 
where  tubercular  material  is  examined. 

"5.  As  these  precautions  would  not  eliminate  fly  in- 
fection by  patients  at  large,  foodstuffs  should  be  pro- 
tected from  flies  which  may  already  have  ingester  tu- 
bercular material." 

According  to  Nuttall  and  Jepson,  the  first  investi- 


164    THE  HOUSE  FLY— DISEASE  CARRIER 

gators  to  study  the  house  fly  in  relation  to  the  possible 
dissemination  of  tubercle  bacillus  were  Spillman  and 
Haushalter  in  1887.  They  found  tubercle  bacilli  in  the 
intestinal  contents  of  flies  and  in  their  dejections  as 
well,  the  flies  having  fed  upon  tubercular  sputum.  They 
also  show  that  Hofmann,  in  a  paper  published  in  1888 
on  the  spread  of  tuberculosis  through  house  flies,  re- 
ported certain  observations  under  natural  conditions. 
He  examined  flies  captured  in  the  room  of  a  tubercu- 
lous patient  and  found  bacilli  in  four  out  of  six  flies  ex- 
amined, as  well  as  in  the  fly-specks  scraped  from  the 
walls,  door  and  furniture  of  the  room.  Similar  ob- 
servations are  reported  to  have  been  made  by  Hay  ward 
(1904),  Buchanan  (1907)  and  Cobb  (1905). 

Much  stress  is  now  being  laid  upon  the  alimentary 
transmission  of  tuberculosis,  and  in  view  of  the  facts 
just  stated  it  can  hardly  be  denied  that  the  house  fly  is 
a  serious  danger  in  the  carriage  of  the  "white  plague." 

ANTHRAX 

Anthrax  is  an  infectious  and  usually  fatal  bacterial 
disease  of  cattle,  sheep,  and  other  animals,  producing 
ulcerations.  It  occasionally  occurs  in  man,  and  is  usu- 
ally known  by  the  name  "malignant  pustule."  It  has 
been  shown  by  many  authors  that  the  bacillus  of  an- 
thrax is  carried  by  several  species  of  flies,  and  Celli  of 
Rome,  as  early  as  1888,  found  that  anthrax  bacilli  pass, 
unimpaired  in  virulence,  through  the  alimentary  tract 
of  flies.  Other  observers  have  accomplished  the  trans- 
fer of  anthrax  by  means  of  flies  from  experimental 


CARRIAGE  OF  DISEASE  165 

animals  to  sterilized  culture  plates.  It  seems  perfectly 
demonstrated  that  flies  pick  up  anthrax  bacilli  when 
they  walk  about  and  when  they  feed  upon  infected  ma- 
terial. It  has  not,  however,  been  shown  how  long  they 
may  carry  the  bacillus,  and  it  is  not  known  whether  its 
virulence  is  reduced  by  passage  through  their  bodies. 
Nuttall  suggested  as  early  as  1899  that  it  appears  prob- 
able that  non-biting  flies,  like  the  house  fly,  may,  when 
infected,  spread  anthrax  by  depositing  the  bacilli  upon 
wounds  or  food. 

It  may  be  remarked  incidentally  that  biting  flies,  such 
as  the  stable  fly  (Stomoxys  calcitrant)  or  any  of  the 
gad-flies,  biting  an  animal  affected  by  the  disease,  might 
naturally  be  supposed  to  carry  the  Bacillus  anthracis 
into  the  circulation  of  a  human  being  by  a  puncture 
after  a  short  period,  and  cases  have  been  reported  where 
malignant  pustule  apparently  followed  the  bite  of  some 
fly.  Efforts  to  prove  this  by  experiment  with  biting 
flies  and  guinea-pigs,  however,  have  not  been  successful. 
Nuttall  in  1899  concluded  that  while  it  is  conceivable 
that  infection  may  occur  in  this  way,  it  is  probable  that 
it  is  the  exception  and  not  the  rule. 

YAWS  (Frambcesia  fro  pica) 

Yaws  is  a  tropical  disease,  contagious  and  innocu- 
lable,  characterized  by  the  appearance  of  papules  which 
develop  into  a  fungus-like,  incrusted,  and  excessively 
disagreeable  eruption.  It  is  widely  distributed  through- 
out the  greater  part  of  the  tropical  world,  being  very 
common  in  tropical  Africa,  especially  on  the  west  coast, 


166    THE  HOUSE  FLY— DISEASE  CARRIER 

in  many  of  the  West  Indian  Islands,  in  Ceylon,  Java, 
in  Fiji,  and  Samoa,  and  other  Pacific  islands.  It  oc- 
curs in  China,  but  is  rare  there.  It  is  highly  contagious, 
but  simple  contact  of  the  skin  is  not  sufficient — an 
abraded  surface  is  necessary.  Sir  Patrick  Manson  says 
that  probably  the  virus  is  often  conveyed  by  insect  bites 
or  by  insects  acting  as  go-betweens  and  carrying  it  from 
a  yaw  sore  to  an  ordinary  ulcer;  thus  the  disease  often 
commences  in  a  pre-existing  ulcer.  It  is  neither  hered- 
itary nor  congenital. 

Prof.  E.  W.  Gudger,  of  the  State  Normal  College 
at  Greensboro,  N.  C,  has  called  attention  to  a  very 
early  idea  as  to  the  carriage  of  yaws  by  flies,  on  pages 
385  to  386  of  Dr.  Edward  Bancroft's  "An  Essay  on 
the  Natural  History  of  Guiana  in  South  America," 
published  in  London  in  1769.  Doctor  Bancroft  writes, 
"The  yaws  are  spongy,  fungous,  yellowish,  circular  pro- 
tuberances, not  rising  very  high,  but  of  different  mag- 
nitudes, usually  between  one  and  three  inches  circum- 
ference. These  infest  the  whole  surface  of  the  body 
and  are  commonly  so  contiguous  that  the  end  of  the 
finger  cannot  be  inserted  between  them,  and  a  small 
quantity  of  yellowish  pus  is  usually  seen  adhering  to 
their  surface,  which  is  commonly  covered  with  flies 
through  the  indolence  of  the  negroes.  *  *  *  It  is 
usually  believed  that  this  disorder  is  communicated  by 
the  flies  which  have  been  feasting  on  the  diseased  ob- 
ject to  those  persons  who  have  sores  or  scratches  which 
are  uncovered;  and  from  many  observations  I  think 
this  is  not  improbable,  as  none  ever  receive  this  dis- 


CARRIAGE  OF  DISEASE  167 

order  whose  skins  are  whole;  for  which  reason  the 
whites  are  rarely  infected ;  but  the  backs  of  negroes,  be- 
ing often  raw  by  whipping,  and  suffered  to  remain 
naked,  they  scarce  ever  escape." 

Nuttall  and  Jepson  state  that  Wilson  (1868)  says 
that  the  belief  prevails  in  the  West  Indies  that  this  dis- 
ease is  carried  by  flies.  They  also  show  that  Hirsch 
(1896)  reports  two  cases  in  which  he  thinks  the  dis- 
ease was  conveyed  by  flies.  They  also  quote  Cadet  to 
the  effect  that  lesions  of  the  skin  are  necessary  for  in- 
fection, and  that  this  may  occur  through  direct  contact 
with  infected  clothes  or  flies,  the  latter  transporting 
the  virus  on  their  feet,  which  are  soiled  with  diseased 
secretions. 

The  causative  organism  of  yaws  is  supposed  to  be 
an  extremely  delicate  spirochaete  very  much  like  that 
of  syphilis.  Castellani  (1907)  reports  experimental  in- 
vestigations showing  that  with  monkeys  the  disease  can 
be  conveyed  by  inoculation,  showing  also  that  yaws 
and  syphilis  are  different  diseases.  The  causative  or- 
ganisms of  the  two  diseases  appear  to  be  distinct,  that 
of  yaws  being  called  Spirochceta  pertenuis.  He  makes 
the  statement  that  there  can  be  no  doubt  of  the  con- 
veyance of  the  disease  by  direct  contact  from  person 
to  person,  and  that  under  certain  conditions  it  may  be 
conveyed  by  flies  and  possibly  by  other  insects. 

OPHTHALMIA 

A  number  of  years  ago,  while  studying  the  habits 
of  certain  minute  flies  of  the  genus  Hippelates,  which 


168    THE  HOUSE  FLY— DISEASE  CARRIER 

are  commonly  seen  flying  about  the  eyes  of  domestic 
animals,  the  writer  was  informed  by  the  late  Henry  G. 
Hubbard  that  he  believed  these  little  flies  to  be  respon- 
sible for  the  transfer  of  the  pink-eye  among  the  school 
children  of  Florida.  He  had  known  this  disease  to 
run  rapidly  through  a  school  and  had  observed  that  the 
little  Hippelates  flies  were  always  present  and  were 
much  attracted  to  the  inflamed  eyelids. 

When  this  observation  of  Hubbard's  was  mentioned 
to  Dr.  Lucien  Howe  of  Buffalo,  Doctor  Howe  informed 
the  writer  that  in  his  opinion  the  ophthalmia  of  the 
Egyptians  is  also  transferred  by  flies,  and  presumably 
by  the  house  fly,  and  referred  the  writer  to  a  paper 
which  he  had  read  before  the  Seventh  International 
Congress  of  Ophthalmology  at  Wiesbaden  in  1888.  He 
referred  to  the  extraordinary  prevalence  of  purulent 
ophthalmia  among  the  natives  up  and  down  the  River 
Nile  and  to  the  extraordinary  abundance  of  the  flies 
in  that  country.  He  spoke  of  the  dirty  habits  of  the 
natives  and  of  their  remarkable  indifference  to  the  vis- 
its of  flies,  not  only  children,  but  adults  allowing  flies 
to  settle  in  swarms  about  their  eyes  sucking  the  secre- 
tions and  never  making  any  attempt  to  drive  them 
away.  Doctor  Howe  called  attention  to  the  fact  that 
the  number  of  cases  of  this  eye  disease  always  increases 
when  the  flies  are  present  in  the  greatest  numbers  and 
that  the  eye  trouble  is  most  prevalent  in  the  place  where 
the  flies  are  most  numerous.  In  the  desert  where  flies 
are  absent,  eyes  as  a  rule  are  unaffected.  He  made  an 
examination  of  the  flies  captured  upon  diseased  eyes, 


CARRIAGE  OF  DISEASE  169 

and  found  on  their  feet  bacteria  which  were  similar  to 
those  found  in  the  conjunctiva!  secretion. 

At  the  time  when  Doctor  Howe  told  the  writer  of 
this  paper,  the  latter  was  so  rilled  with  the  idea  that 
horse  manure  was  far  and  away  the  most  abundant 
producer  of  house  flies  that,  inasmuch  as  there  are  com- 
paratively few  horses  in  the  Nile  Valley,  he  was  in- 
clined to  suspect  that  the  fly  concerned  in  the  carriage 
of  this  disease  as  pointed  out  by  Doctor  Howe  might 
be  some  other  species  breeding  by  preference  in  camel 
dung  or  perhaps  in  some  other  substance.  He  there- 
fore sent  to  Egypt  and  secured  specimens  of  the  flies 
commonly  swarming  about  the  eyes  of  ophthalmic  pa- 
tients, and  on  their  receipt  in  Washington  they  were 
readily  determined  as  Musca  domestica  by  Mr.  D.  W. 
Coquillett  of  the  Bureau  of  Entomology. 

Nuttall  and  Jepson  show  that  Budd,  as  early  as  1862, 
considered  that  it  was  fully  proven  that  flies  served  as 
the  carriers  of  Egyptian  ophthalmia,  and  Laveran,  in 
1880,  writing  of  Biskra,  says  the  same.  These  writers 
also  point  out  that  Braun  (1882),  Demetriades  (1894) 
and  German  (1896)  agree  that  gonorrheal  and  other 
infections  of  the  eye  may  be  carried  by  flies.  They 
state  that  Welander  (1896)  observed  an  interesting 
case  where  an  old  bedridden  woman  in  a  hospital  be- 
came infected.  It  seems  that  her  bed  was  alongside 
that  of  another  patient  who  had  blennorrhea,  but  that 
a  screen  which  did  not  reach  to  the  ceiling  separated 
the  beds.  Thus  all  means  of  infection  except  through 
the  agency  of  flies  was  apparently  absent.  The  inves- 


170    THE  HOUSE  FLY— DISEASE  CARRIER 

tigator  found  that  flies  bore  living  gonococci  upon  their 
feet  three  hours  after  they  had  been  soiled  with  secre- 
tion, since  they  infected  sterilized  plates  with  which 
they  came  in  contact. 

Nuttall  and  Jepson  conclude  their  consideration  of 
ophthalmia  with  the  following  statement:  "The  evi- 
dence regarding  the  spread  of  Egyptian  ophthalmia  by 
flies  appears  to  be  conclusive,  and  the  possibility  of 
gonorrheal  secretions  being  conveyed  by  flies  cannot  be 
denied." 

DIPHTHERIA 

Nuttall  and  Jepson  have  been  able  to  find  only  one 
reference  to  the  dissemination  of  Bacillus  diphtheria 
by  flies.  They  state  that  Dickinson  ( 1907)  cites  Smith 
( 1898)  as  having  tried  the  oft- repeated  type  of  experi- 
ment of  allowing  house  flies  to  walk  over  infected  ma- 
terial and  then  over  sterile  media.  A  positive  result 
was  obtained  as  a  matter  of  course.  The  authors  state 
that  there  is  no  evidence  that  under  natural  conditions 
flies  have  anything  to  do  with  the  spread  of  diphtheria, 
but  indicate  that  it  is  of  course  conceivable  that  they 
may  convey  the  infection  under  suitable  conditions. 

SMALL-POX 

The  only  published  account  of  the  possible  relation 
of  flies  to  small-pox  cited  by  Nuttall  and  Jepson  is 
taken  by  them  from  a  paper  by  Hervieux,  read  June  5, 
1904,  to  the  Academy  of  Medicine  at  Paris,  in  which 
he  states  that  Laforgue  at  a  locality  in  the  province  of 
Constantine  observed  that  during  an  epidemic  of  small- 


CARRIAGE  OF  DISEASE  171 

pox  the  children  who  were  attacked  all  lived  in  the 
southwest  of  the  village,  the  northern  part  of  the  vil- 
lage remaining  free  from  the  disease.  This  distribu- 
tion was  thought  to  be  due  to  the  direction  of  the  pre- 
vailing winds,  and  observations  were  made  to  the  effect 
that  flies  and  mosquitoes  were  distributed  with  the 
wind.  Laforgue  himself  believed  that  flies  played  an 
important  part  in  the  spread  of  the  virus  of  small-pox. 

PLAGUE 

So  much  is  now  known  concerning  the  specific  origin 
of  bubonic  plague  and  concerning  its  carriage  by  the 
several  species  of  fleas  which  occur  upon  rats,  which 
are  also  subject  to  the  same  disease,  that  house  flies 
cannot  be  claimed  to  be  of  importance  in  this  connec- 
tion ;  but  old  writers  have  noted  the  occurrence  of  flies 
in  large  numbers  in  plague  years,  and  one  of  them  at 
least  considered  that  house  flies  carried  the  disease, 
simply  from  the  fact  that  they  visited  food  after  they 
had  abandoned  plague  patients. 

Nuttall  and  Jepson  call  attention  to  the  fact  that 
Yersin,  in  writing  upon  bubonic  plague  at  Hong-Kong 
in  1894,  stated  that  he  saw  many  dead  flies  lying 
around  in  his  laboratory  when  he  was  conducting  au- 
topsies on  animals  killed  by  the  plague.  He  demon- 
strated by  inoculation  into  animals  that  a  dead  fly  con- 
tained virulent  plague  bacilli. 

Nuttall  himself  had  in  1897  already  experimented 
with  the  house  fly,  feeding  it  upon  organs  of  animals 
dead  by  the  plague.  He  found  that  the  flies  might 


172    THE  HOUSE  FLY— DISEASE  CARRIER 

survive  for  eight  days  after  feeding  on  infected  organs 
and  that  they  still  harbored  virulent  bacilli  forty-eight 
hours  and  more  after  they  were  transferred  to  clean 
vessels.  At  high  temperatures  the  infected  flies  died 
more  rapidly  than  controlled  flies  which  were  fed  on 
the  organs  of  healthy  animals,  from  which  he  concluded 
that  the  plague  bacillus  may  be  fatal  to  house  flies  un- 
der suitable  conditions  of  temperature.  This  possibly 
accounted  for  the  dead  flies  noted  by  Yersin  in  his 
Hong-Kong  laboratory.  Nuttall  also  points  out  that 
a  French  observer,  Matignon,  observed  in  1898  that 
flies  died  in  large  numbers  in  Mongolia  during  plague 
times. 

TROPICAL  SORE 

This  disease  is  referred  to  by  Nuttall  and  Jepson 
under  this  name  and  also  under  the  name  "Bouton  de 
Biskra."  They  state  that  it  is  asserted  by  Laveran 
and  Seriziat  (1880)  that  flies  convey  this  trouble.  In 
other  localities,  the  natives  declare  that  the  disease  is 
caused  by  the  bite  of  certain  insects.  It  is  said  that 
Seriziat  asserts  that  a  lesion  of  the  skin  is  always  neces- 
sary for  an  infection  to  take  place,  and  that  it  unques- 
tionably results  at  times  as  a  consequence  of  mosquito 
bite.  Laveran  in  his  observations  at  Biskra  stated  that 
from  September  to  October  the  slightest  wound  tends 
to  be  transformed  into  the  bouton.  He  has  seen  it  graft 
itself  upon  pustules  of  acne,  upon  vaccine  pustules,  and 
upon  wounds  following  burns  or  blisters.  He  does  not 
doubt  that  it  is  carried  by  flies  on  their  feet  and  on  their 
beaks. 


CARRIAGE  OF  DISEASE  173 

PARASITIC  WORMS 

Nuttall  and  Jepson  refer  to  the  experiments  made  by 
Grassi  in  1883.  When  he  broke  up  segments  of  the 
human  tapeworm  in  water  after  these  had  been  pre- 
served some  months  in  alcohol,  he  saw  that  the  flies 
came  and  sucked  up  the  eggs  with  the  water  and  that 
the  eggs  were  passed  unaltered  through  the  bodies  of 
the  flies.  He  had  the  same  results  with  the  eggs  of  Ox- 
yuris,  one  of  the  so-called  "thread-worms"  or  "pin- 


worms." 


While  experimenting  with  the  unsegmented  eggs  of 
still  another  of  the  genus  Trichocephalus  (one  of  the 
so-called  "whip  worms,"  having  a  long,  slender  neck 
like  a  whip  lash),  which  were  placed  upon  a  table,  he 
saw  flies  feed  on  them  and  later  found  the  eggs  in  the 
fly-specks  which  had  been  deposited  in  the  kitchen  on 
the  floor  beneath,  ten  yards  away  from  the  place  where 
the  insects  had  been  fed.  He  caught  some  flies  whose 
intestines  were  full  of  the  eggs. 

Nuttall  also  records  an  observation  of  Dr.  C.  W. 
Stiles,  of  the  Public  Health  and  Marine-Hospital  Ser- 
vice, which  had  been  sent  to  him  in  a  personal  letter, 
showing  that  Stiles  had  placed  fly  larvae  with  the  fe- 
male of  Ascaris  lumbricoides  (the  most  abundant  of 
the  "round  worms/'  which  inhabit  the  small  intestine, 
especially  with  children),  which  they  devoured  together 
with  her  eggs.  He  afterwards  found  that  the  larvae 
and  the  adult  flies  contained  the  eggs  of  the  Ascaris. 
The  experiment  was  made  in  very  hot  weather.  The 


174    THE  HOUSE  FLY— DISEASE  CARRIER 

Ascaris  eggs  developed  rapidly  and  were  found  in  dif- 
ferent stages  of  development  in  the  insects,  thus  prov- 
ing that  the  flies  may  serve  as  disseminators  of  the  para- 
site. "Provided  that  the  eggs  attained  the  proper  stage 
of  development,  the  fly,  acting  simply  as  a  carrier, 
might  convey  the  parasite  to  man  by  falling  into,  or 
depositing  its  excreta  on,  the  food." 


IV 

REMEDIES  AND  PREVENTIVE  MEASURES 

TO  avoid  only  the  danger  from  flies,  you  must  de- 
stroy or  protect  from  them  all  substances  contain- 
ing disease  germs.  This  is  done  in  large  part,  so  far  as 
intestinal  diseases  are  concerned,  by  the  water-closet 
system  in  cities,  and  it  may  be  done  by  sanitary  privies 
in  villages  and  country  houses  and  in  mining  and  con- 
struction camps ;  and  also  by  properly  cared-for  trenches 
or  latrines  at  temporary  army  posts.  To  avoid  danger 
from  flies  in  the  case  of  lung  troubles,  the  proper  care 
of  the  sputa  is  essential. 

To  avoid  the  nuisance  of  flies  it  becomes  necessary 
practically  to  get  rid  of  them,  and  in  doing  this  of 
course  we  get  rid  of  the  danger  at  the  same  time.  It 
has  always  seemed  to  the  writer  that  the  truest  and 
simplest  way  of  attacking  the  fly  problem  is  to  prevent 
them  from  breeding,  by  the  treatment  or  abolition  of  all 
places  in  which  they  can  breed.  To  permit  them  to 
breed  undisturbed  and  in  countless  numbers,  and  to 
devote  all  our  energy  to  the  problem  of  keeping  them 
out  of  our  dwellings  or  to  destroying  them  after  they 
have  once  entered  in  spite  of  all  obstacles,  seems  the 
wrong  way  to  go  about  it.  To  the  individual  who  has 
control  of  the  grounds  for  some  distance  about  his 
abiding  place,  the  former  method  is  undoubtedly  the 

175 


176    THE  HOUSE  FLY— DISEASE  CARRIER 

best,  and  it  would  also  undoubtedly  be  the  best  in  any 
event  if,  by  co-operation  of  the  residents  or  by  the 
active  efforts  of  a  central  body,  like  the  boards  of  health 
in  cities,  it  were  possible  to  do  thorough  work  with  the 
breeding  places. 

In  cities  and  in  towns,  however,  where  the  requisite 
co-operation  cannot  be  obtained,  and  where  boards  of 
health  are  still  indifferent,  careful  consideration  must 
be  given  to  the  second  method,  namely,  keeping  flies 
out  or  killing  them  after  they  enter. 

A  third  method  has  been  proposed  and  is  enthusi- 
astically advocated  by  Professor  Hodge,  of  Clark  Uni- 
versity, Worcester,  which  is  based  upon  the  supposed 
time  elapsing  between  the  issuance  of  the  adult  fly  and 
the  period  when  it  lays  its  first  eggs.  Professor  Hodge, 
as  will  be  shown  later,  thinks  that  it  is  quite  possible 
to  trap  these  sexually  immature  adults  during  this 
period,  which  now  seems  comparatively  long,  and  thus 
to  prevent  not  only  their  entrance  into  houses  and  shops 
and  markets,  but  to  destroy  so  many  of  them  that  the 
comparatively  few  which  reach  sexual  maturity  will 
not  be  able  to  lay  their  eggs  in  sufficient  numbers  to 
make  the  next  generation  a  nuisance.  In  other  words, 
he  thinks  that  it  will  be  possible  to  bring  about  such  a 
condition  that  the  manure  pile  may  be  left  undisturbed 
until  it  is  needed  to  fertilize  the  land. 

Whether  this  can  be  done  or  not — and  Professor 
Hodge's  argument  seems  reasonable — will  again  de- 
pend upon  co-operation  in  communities,  although  indi- 
vidual effort  in  isolated  places  may  bring  it  about. 


PREVENTIVE  MEASURES  177 

Success  will  also  to  a  great  degree  depend  upon  the 
applicability  of  Doctor  Hewitt's  isolated  observations 
upon  the  period  between  issuance  and  sexual  maturity 
to  other  seasons  and  to  other  parts  of  the  world. 

SCREENING 

Three  years  ago  I  made  an  attempt  to  estimate  the 
amount  of  money  spent  annually  in  screening  houses 
in  the  United  States.  As  close  an  estimate  as  could 
conscientiously  be  made  seemed  to  indicate  that  more 
than  $10,000,000  are  spent  every  year  for  this  kind 
of  protection  against  flies  and  mosquitoes.  In  fly-rid- 
den localities  the  expense  is  undoubtedly  justified,  since 
the  majority  of  the  flies  are  kept  out  by  careful  screen- 
ing. No  system  of  screening,  however,  seems  to  be  so 
perfect  as  to  keep  them  all  out.  They  get  in,  one  way 
or  another,  in  spite  of  care;  even  where  double  doors 
are  used  they  eventually  gain  entrance.  In  the  summer 
time,  in  country  houses  having  large  open  fireplaces 
disused  during  warm  weather,  flies  undoubtedly  come 
down  the  chimney,  and  it  is  necessary  under  those  con- 
ditions to  arrange  a  wire  screen  before  the  open  fire- 
place in  such  a  way  that  it  can  easily  be  removed  on  a 
cold  day. 

The  whole  expense  of  screening,  however,  should  be 
an  unnecessary  one,  just  as  efforts  to  destroy  flies  in 
houses  should  be  unnecessary.  Their  breeding  should 
be  stopped  to  such  an  extent  that  all  these  things  would 
be  useless. 


178    THE  HOUSE  FLY— DISEASE  CARRIER 

FLY  TRAPS  AND  FLY  POISONS 

In  the  effort  to  destroy  the  flies  which  have  gained 
access  to  houses  many  devices  have  been  invented,  and 
many  of  them  have  been  patented.  Nearly  all  of  the 
traps  which  are  on  the  market  are  reasonably  effective, 
and  it  will  be  unfair  to  mention  any  one  or  two  or  three 
where  so  many  are  good.  They  are  all  cheap  and  it 
is  a  simple  matter  for  one  to  test  them  one  after  an- 
other until  the  most  satisfactory  one  is  found.  Very 
effective  traps  are  made  of  sticky  fly  paper — flat  sheets 
to  be  laid  on  tables,  bookcases,  or  in  other  places. 

A  recent  idea,  gained  from  the  observation  that  flies 
in  rooms  where  there  is  no  food  seem  frequently  to 
rest  by  preference  upon  vertically  hanging  cords  of 
window  curtains,  on  the  supports  of  chandeliers,  and 
objects  of  that  general  character,  has  resulted  in  several 
arrangements  by  which  strips  of  sticky  fly  paper  are 
suspended  in  this  way,  and  this  has  given  in  many 
cases  satisfactory  results.  One  of  the  writer's  friends, 
in  experimenting  with  one  of  these  devices,  examined 
the  room  carefully  and  noted  eleven  flies.  After  the 
apparatus  was  hung  he  found  rather  to  his  surprise 
that  he  had  caught  thirteen  flies!  He  became  rather 
enthusiastic  over  the  merits  of  the  device.  These 
sticky  fly  papers  are  not  poisoned,  and  depend  for  their 
efficacy  upon  the  catching  of  the  flies. 

Poisoned  fly  papers  were  at  one  time  very  much  in 
use  and  are  still  in  some  localities.  The  old  dispensa- 
tories give  an  account  of  a  harmless  fly  poison  prepared 


PREVENTIVE  MEASURES  179 

in  the  following  way :  ''Macerate  during  twenty-four 
hours  i  ,000  parts  of  quassia  wood  with  5,000  parts 
of  water,  then  boil  for  half  an  hour;  set  aside  for 
twenty- four  hours  and  press.  Mix  the  liquid  with  1 50 
parts  of  molasses,  and  evaporate  to  200  parts.  A 
weaker  decoction  of  the  quassia  does  not  kill  the  flies. 
From  this  the  fly  water  or  fly  plate  is  prepared  as  fol- 
lows :  Mix  when  needed  and  dispense  without  filter- 
ing, 200  parts  of  syrup  of  quassia,  fifty  parts  of  alcohol 
and  750  parts  of  water.  It  is  used  by  moistening  with 
the  mixture  a  cloth  or  filtering  paper  on  a  plate." 

The  native  ore  of  speiss  cobalt  is  found  in  commerce 
under  the  name  of  flystone,  and  was  at  one  time  ex- 
tensively used  for  poisoning  flies  by  roughly  grinding 
it  and  putting  a  small  quantity  in  a  saucer  with  sweet- 
ened water. 

It  is  possible  to  poison  flies  rather  satisfactorily  by 
putting  a  lump  of  sugar  in.  a  saucer  partly  filled  with 
water  and  adding  white  arsenic.  This,  of  course,  is 
dangerous  where  there  are  children  or  house  dogs  or 
cats  about. 

Of  the  unpatented  fly  traps,  a  device  was  recom- 
mended by  Mr.  P.  J.  Parrott,  Entomologist  of  the 
Kansas  Experiment  Station,  in  Bulletin  99  of  the  Sta- 
tion (October,  1900),  as  follows: 

"The  department  of  entomology,  after  experimenting 
upon  various  mechanical  devices  for  catching  flies,  has 
contrived  a  trap  and  recommended  it  for  trial  on  ac- 
count of  its  effectiveness  and  cheapness.  Anybody 
with  an  average  amount  of  mechanical  ingenuity  can 


180    THE  HOUSE  FLY— DISEASE  CARRIER 

make  and  attach  the  trap,  with  a  cost  of  but  a  few 
cents.  It  is  made  as  follows: 

"Take  a  flat  strip  of  tin  two  and  one-fourth  inches 
wide  and  one  and  one-half  inches  longer  than  the  dis- 
tance between  the  side  rail  or  stile  and  middle  rail  of 
the  sash,  as  from  c  to  d,  Fig  3,  which  in  this  case  meas- 
ured twenty-one  inches.  For  this  window,  the  strip 
must  be  twenty-two  and  one-half  inches  in  length. 
With  the  tin  lying  on  the  flat  surface,  bend  the  tin 
along  the  lines  ab  and  cd,  Fig.  i,  which  are  three- 
quarters  of  an  inch  from  their  respective  sides,  so  that 
the  space  abdc  forms  the  bottom  of  a  box  and  the  lat- 
eral parts  the  sides.  To  close  the  ends,  cut  small  in- 
cisions three-quarters  of  an  inch  deep  at  the  points 
a,  b,  c,  and  d,  as  ay  and  ex,  Fig.  i.  Bend  the  flaps 
thus  made  at  right  angles  to  their  respective  parts. 
We  then  have  a  box  twenty-one  inches  long,  three- 
quarters  of  an  inch  wide,  and  three-quarters  of  an  inch 
deep,  as  at  Fig.  2. 

"To  make  the  box  water-tight,  solder  the  joints,  or 
if  solder  is  not  handy  try  moistened  plaster  of  Paris. 
When  properly  made,  the  box  should  fit  snugly  be- 
tween the  middle  and  side  rail  or  style.  The  corners 
should  be  square  and  the  edges  straight,  so  as  to  leave 
no  passageways  between  the  box  and  the  glass.  The 
box  should  rest  on  top  of  the  bottom  rail,  and  can  be 
held  in  place  by  two  or  three  tacks  or  pins  thrust  into 
the  rail  from  the  back  side.  When  the  pane  is  very 
large  it  is  well  to  attach  another  trap  half  way  between 
the  top  and  the  bottom. 


PREVENTIVE  MEASURES 


181 


* 


i£ 


II1IIIIIIIIIIMIIHIN'    111/'  III'   IIHHIi  [III 


Fig.  19.— Details  of  window  trap.     (Redrawn  from  Parrott.) 


182    THE  HOUSE  FLY— DISEASE  CARRIER 

"After  the  traps  have  been  attached,  some  substance 
should  be  put  into  them  that  will  either  kill  the  insect 
upon  falling  into  it,  or  on  account  of  its  sticky  nature 
will  hold  the  insect  so  that  it  cannot  escape.  For  the 
first,  kerosene,  kerosene  emulsion,  soapsuds  and  py- 
rethrum  are  the  best ;  and  for  the  second,  molasses,  or 
a  mixture  of  castor-oil  and  resin.  For  general  use,  the 
soapsuds  are  to  be  recommended.  When  using  the 
liquids,  fill  the  traps  two-thirds  full. 

'There  should  be  one  trap  for  every  pane  of  glass 
of  at  least  one  window  in  the  house.  For  instance, 
when  the  sash  contains  two  panes  of  glass,  as  in  the 
cut,  there  should  be  two  traps,  one  at  the  base  of  each 
pane.  When  the  sash  contains  four  panes,  there  should 
be  four  traps,  two  on  the  bottom  rail  and  two  on  the 
cross-bars  or  munting.  It  is  not  necessary  to  apply 
traps  to  all  the  windows.  Attach  traps  to  one  or  two 
windows  in  the  sunny  part  of  the  house,  and  pull  down 
the  blinds  of  the  remaining  windows.  The  flies  will 
seek  the  lighted  rooms,  and  especially  the  windows. 

"When  the  traps  are  full  of  flies,  remove  them  from 
their  fastenings,  empty  out  their  contents,  and  fill  them 
with  fresh  material. 

"A  temporary  trap  can  be  made  of  flexible  card- 
board, following  the  same  directions  as  for  those  made 
of  tin.  Use  glue  or  pins  to  fasten  the  ends.  To  render 
the  trap  water-proof,  paint  the  inside  with  melted  par- 
affin. This  will  hold  any  of  the  above  remedies  except 
the  pure  kerosene." 

A  correspondent,  Dr.  D.  S.  Hager,  has  made  a  sue- 


PREVENTIVE  MEASURES  183 

cessful  fly  trap  which  cost  for  material  about  fifteen 
cents,  and  writes  that  any  bright  boy  can  make  one  of 
them  in  an  hour  or  two.  He  took  two  pieces  of  board 
one  inch  thick  and  about  a  foot  square;  tacked  them 
together,  sawed  them  round,  and  in  the  center  sawed 
a  hole  eight  inches  in  diameter.  He  then  separated 
the  boards,  and  into  one  he  fitted  a  funnel-shaped  piece 
of  wire  screen  about  ten  inches  high,  which  was  fas- 
tened to  the  board  with  tacks  driven  on  the  inside  of 
the  round  hole  and  fastened  together  funnel-shaped 
with  a  strand  of  the  wire  selvage.  A  small  hole,  large 
enough  to  admit  a  lead  pencil,  was  left  at  the  apex  of 
the  funnel  for  the  flies  to  creep  through.  He  then 
tacked  a  piece  of  wire  netting,  eighteen  inches  wide,  to 
the  outside  circumference  of  each  of  the  round  boards,  . 
with  the  funnel-shaped  wire  on  the  inside.  The  out- 
side of  the  wire  was  again  fastened  with  the  selvage 
of  the  wire.  On  the  top  he  tacked  a  piece  of  wire 
screen  in  such  a  way  that  he  could  readily  remove  it  to 
empty  out  the  flies.  He  then  nailed  lengthwise  on  the 
outside  of  the  trap  a  few  laths  to  make  it  more  firm. 
He  then  made  feet  by  screwing  into  the  bottom  piece 
containing  the  funnel  four  wire  coat-hangers  about  five 
inches  high. 

He  placed  these  traps  (he  made  two  at  the  same 
time)  one  on  each  side  of  the  front  porch,  and  under 
each  he  placed  a  plate  with  some  sugar  on  it  and  a  cup 
of  sweetened  water  in  the  plate.  Flies  were  attracted 
by  the  sugar  and  sweetened  water,  and  as  they  flew 
over  the  bait  they  crawled  through  the  hole  in  the  fun- 


184    THE  HOUSE  FLY— DISEASE  CARRIER 

nel  up  into  the  trap.  The  traps  caught  many  each  day, 
and  were  soon  filled  with  a  buzzing  mass.  He  suggests 
that  a  trap  of  this  kind  should  be  placed  near  the  door 
of  a  house,  as  flies  will  congregate  at  the  top  of  the 
screen  door  and  enter  the  house  when  the  door  is 
opened. 

He  caught  quarts  of  flies,  and  at  first  killed  them  by 
pouring  scalding  water  over  them,  but  this  had  a  detri- 
mental effect  upon  the  wood  and  wire  of  the  trap,  so 
he  killed  them  by  fumigating  with  sulphur,  setting  a 
large  paper  packing  box  over  all,  destroying  them  in 
this  way  in  about  two  and  a  half  minutes. 

Many  different  kinds  of  fly  traps  are  used  in  differ- 
ent parts  of  the  world.  We  read,  for  example,  in  the 
Journal  of  the  Department  of  Agriculture  of  Western 
Australia  that  flies  may  be  effectually  destroyed  by 
putting  a  half  spoonful  of  black  pepper  in  powder  on 
a  teaspoon ful  of  brown  sugar  and  one  teaspoon ful  of 
cream.  Mix  all  together  and  place  in  a  room  where 
flies  are  troublesome  and  it  is  said  they  will  soon  dis- 
appear. 

Dr.  Paul  Freer  of  Manila  tells  the  writer  that  in  the 
Japanese  hospitals  they  take  a  whole  potato  and  stick 
it  full  of  toothpicks,  put  fly  paste  on  the  toothpicks, 
and  hang  the  potatoes  from  the  ceiling  over  the  pa- 
tient's bed  on  a  cord.  The  flies  all  gather  on  the  po- 
tato, and  when  it  is  full  they  throw  the  potato  away 
and  make  a  new  trap.  The  toothpicks  are  placed  about 
one-fourth  of  an  inch  apart,  and  the  potato  presents 
the  appearance  of  a  porcupine. 


PREVENTIVE  MEASURES  185 

Formalin 

Ten  years  or  more  ago,  when  formaldehyd  gas  was 
found  to  be  a  good  germicide,  experiments  were  made 
with  it  against  different  insects  without  success;  but 
the  evaporation  of  formalin  has  continued  to  be  of  use 
in  sick  rooms.  Quite  by  accident  it  was  discovered  by 
different  people,  apparently  in  different  parts  of  the 
world,  that  a  formalin  solution  is  a  good  mixture  with 
which  to  poison  flies  in  the  house.  So  far  as  we  know, 
the  first  person  in  this  country  to  ascertain  this  was 
Mr.  C.  H.  Popenoe,  who  at  that  time  was  at  the  Kan- 
sas Agricultural  College.  In  the  summer  of  1903,  dur- 
ing the  prevalence  of  an  unusual  number  of  house  flies, 
while  mixing  a  solution  of  formaldehyd  for  the  pres- 
ervation of  insects  (four  per  cent,  formaldehyd,  or  di- 
lution to  ten  per  cent,  commercial),  a  quantity  of  the 
mixture  was  left  in  a  mixing  dish  on  the  table.  Sev- 
eral flies  were  noticed  to  alight  and  drink  of  the  mix- 
ture, quickly  succumbing  to  its  influence.  A  quantity 
was  therefore  placed  on  a  deep  plate  and  set  upon  the 
table.  This  remained  on  the  table  all  the  afternoon, 
and  in  the  evening  was  surrounded  by  many  dead  flies. 
The  room  was  practically  cleared  of  the  pests.  The 
dish  of  formaldehyd  was  used  many  times  during  that 
summer  and  in  subsequent  years  with  excellent  effect 
as  a  fly  poison.  The  flies  seemed  not  to  object  to  the 
presence  of  the  formalin,  drinking  the  water  with  avid- 
ity and  dying  close  to  the  plate  or  saucer,  where  they 
were  readily  swept  up. 


186    THE  HOUSE  FLY— DISEASE  CARRIER 

Some  one  else  in  England  and  possibly  some  one 
else  in  France  seem  to  have  discovered  the  same  fact 
in  very  much  the  same  way.  According  to  Galli- 
Valerio  (1910),  a  ten-per-cent.  formalin  solution  has 
been  recommended  by  certain  European  writers.  Tril- 
lat  and  Legendre,  for  example,  advised  ten-per-cent. 
formalin  solution  with  the  addition  of  twenty  per  cent, 
milk.  The  Fly  Committee  of  the  Merchants'  Associa- 
tion of  New  York,  on  the  basis  of  an  item  in  the  Lon- 
don Lancet,  have  advised  the  use  of  formaldehyd.  A 
number  of  correspondents,  however,  have  written  that 
they  found  it  unavailing.  Dr.  Daniel  S.  Hager,  of 
Chicago,  for  example,  used  formaldehyd  in  water  and 
also  formaldehyd  in  milk ;  a  few  flies  were  found  about 
the  receptacle,  but  the  results  as  compared  with  the 
results  of  fly  paper  were  insignificant. 

Hodge  (1911)  states  that  he  has  been  successful 
in  the  use  of  a  teaspoonful  of  formalin  to  a  teacupful 
of  water.  He  fills  a  big  bottle  with  the  mixture,  in- 
verts it  in  a  saucer  and  mounts  the  whole  in  a  most 
likely  place.  Sweetening  it  or  mixing  it  with  milk  or 
other  foods  to  make  it  more  attractive  will,  he  says, 
result  in  the  destruction  of  flies. 

Herms,  of  the  University  of  California  (1910), 
states  that  formaldehyd  has  given  thorough  satisfaction 
as  a  substitute  for  poisons.  He  points  out  that  it  is 
non-poisonous  to  man,  and  may  therefore  be  used  with 
impunity  around  food.  It  is  a  powerful  germicide  and 
does  not  injure  delicate  fabrics.  He  states  that  forma- 
lin as  purchased  in  the  drug  store  is  in  about  forty-per- 


PREVENTIVE  MEASURES  187 

cent,  solution  and  should  be  diluted  with  water  down 
to  five  per  cent,  or  eight  per  cent. ;  in  other  words,  add 
five  to  six  times  as  much  water.  This  solution,  he 
says,  should  be  sweetened  with  sugar  or  made  attractive 
by  adding  milk. 

He  advises  partly  filling  a  shallow  vessel,  such  as  an 
individual  butter  dish,  and  placing  it  upon  the  table 
or  in  the  show  window.  He  states  that  the  flies  drink 
this  material  and  die  not  far  from  the  containers.  In 
the  dining-room  where  there  is  water,  milk,  or  other 
liquid  food,  flies  are  said  not  to  be  so  greatly  at- 
tracted to  the  formalin,  but  where  this  is  made  the 
only  source  of  drink  for  the  insects  the  results  are 
said  to  be  remarkable.  Herms  recommends  that  all 
other  liquids  except  the  formaldehyd  dishes  in  a 
given  room  should  be  removed  or  securely  covered 
in  the  evening,  so  that  the  flies  have  only  the  formal- 
dehyd to  drink  early  in  the  morning  when  they  begin 
to  fly. 

Some  careful  experiments  were  tried  during  early 
February,  1911,  at  New  Orleans,  La.,  at  the  request 
of  the  writer,  by  Mr.  T.  C.  Barber.  Mr.  Barber's  notes 
indicate  success.  The  mixture  used  was  formaldehyd 
(forty-five  per  cent.),  two  ounces;  sugar,  two  ounces; 
water,  ten  ounces.  On  February  i4th  he  placed  some 
of  this  solution  in  an  open  saucer  in  the  show  window 
of  a  grocery  store,  where  a  few  flies  were  present. 
After  being  left  about  one  hour,  seven  dead  flies  were 
found  in  the  window,  which  had  previously  been  thor- 
oughly cleaned.  He  then  placed  the  material  in  two 


188    THE  HOUSE  FLY— DISEASE  CARRIER 

saucers  with  a  piece  of  bread  in  each.  The  bread 
soaked  up  the  solution  until  it  was  saturated,  and  was 
left  over  night.  The  next  morning  a  large  number  of 
dead  flies  were  found  in  the  neighborhood  of  the  sau- 
cers, and  were  removed.  The  next  day  many  more 
dead  flies  were  found,  and  very  few  could  be  found  in 
the  shop. 

On  February  I5th,  he  placed  some  formalin  mixture 
in  a  petri  dish  on  one  of  the  meat  shelves  of  a  private 
meat  market.  Flies  were  very  abundant.  He  had  no 
bread  to  put  in,  and  so  went  down  to  a  corner  grocery 
about  one  square  away  to  get  some.  He  was  absent 
ten  minutes,  and  on  returning  found  about  one  hundred 
dead  flies  on  the  table  where  the  solution  had  been 
placed.  The  next  day  he  examined  the  place  in  the 
morning,  and  found  hundreds  of  dead  flies  lying 
around,  and  the  numbers  in  the  room  were  reduced 
very  materially.  The  test  was  conducted  under  fa- 
vorable conditions,  and  gave  excellent  results.  Other 
experiments  by  Mr.  Barber  produced  similar  results. 

Pyrethrum  and  Carbolic  Acid 

The  fly-fighting  committee  of  the  American  Civic 
Association  recommend  the  burning  of  pyrethrum 
powder  and  also  the  dropping  of  twenty  drops  of  car- 
bolic acid  upon  a  hot  shovel,  stating  that  the  vapor  kills 
the  flies.  The  Secretary  of  the  Association,  Mr.  Wat- 
rous,  informs  the  writer  that  correspondents  have  com- 
plained that  neither  the  pyrethrum  nor  the  carbolic 
acid  was  in  the  least  effective.  I  have  never  tried  the 


PREVENTIVE  MEASURES  189 

carbolic  acid,  but  pyrethrum  powder  is  certainly  ef- 
fective when  at  all  pure. 

Many  of  the  so-called  pyrethrum  or  Persian  insect 
powders  sold  in  the  shops  are  impure.  The  powder 
itself  is  made  from  the  ground  flower-heads  of  two 
species  of  the  genus  pyrethrum,  which  are  composite 
plants  not  unlike  the  common  ox-eye  daisy.  It  is  a 
not  uncommon  practice  for  makers  of  these  powders 
to  grind  the  stems  as  well  as  the  flower-heads,  thus 
producing  a  dilution  which  greatly  lessens  the  effect 
of  the  powder.  The  insecticidal  element  in  this  pow- 
der seems  to  be  an  oleo-resin,  and  therefore  a  freshly 
ground  powder  is  more  effective  than  an  old  one.  In 
most  of  the  pyrethrum  powders  to  be  found  in  the 
shops  the  heads  have  been  imported  from  Europe  and 
ground  in  this  country. 

There  are,  however,  powders  of  a  somewhat  higher 
price  made  from  pyrethrum  flower-heads  grown  in 
California  in  the  vicinity  of  Stockton.  These  appear 
to  be  the  freshest  and  strongest,  but  they  cost  more. 
It  has  been  the  experience  of  the  writer  that  these 
California  powders  are  effective  against  house  flies 
either  when  puffed  into  the  air  or  when  burned  by 
purring  through  a  gas  jet,  or  by  making  moistened 
cones  put  upon  earthen  dishes  and  ignited  at  the  top. 

REPELLENTS 

Flies  do  not  seem  to  be  repelled  by  odors  to  the  same 
extent  that  mosquitoes  are.  Some  old  ideas  in  this 
direction,  however,  may  be  mentioned.  It  is  stated 


190    THE  HOUSE  FLY— DISEASE  CARRIER 

that  the  butchers  of  Geneva  have  from  time  immemorial 
prevented  flies  from  approaching  the  meat  which  they 
expose  for  sale  by  the  use  of  laurel  oil.  This  oil — 
the  odor  of  which,  although  a  little  strong,  is  not  very 
offensive — is  said  to  drive  away  flies,  and  they  are 
said  not  to  come  near  walls  which  have  been  rubbed 
with  it.  Furthermore,  an  item  in  the  Journal  of  the 
Department  of  Agriculture  of  Western  Australia  states 
that  flies  may  be  kept  out  of  stables  by  using  sawdust 
which  is  saturated  with  carbolic  acid  diluted — one  part 
of  the  acid  to  one  hundred  parts  of  the  water.  It  is 
said  that  this  sawdust  scattered  about  stables  keeps  all 
flies  away. 

The  idea  prevails  in  some  parts  of  the  country  that 
the  hop  vine  grown  over  a  country  house  keeps  the 
flies  away.  Positive  testimony  to  this  effect  has  come 
to  the  writer  from  several  correspondents,  but  he  has 
not  tested  it  and  mentions  it  on  hearsay  evidence  only. 
An  American  correspondent  who  lived  in  Dalmatia, 
for  example,  was  troubled  by  flies,  and  was  told  by 
natives  to  grow  hop  vines  over  the  side  of  the  house 
towards  which  the  flies  appeared  to  come.  She  did 
so,  and  states  that  the  fly  invasion  was  stopped  after 
the  vines  reached  a  certain  height.  There  was,  how- 
ever, possibly  some  explanation  of  this  aside  from  the 
hop  plants. 

SEARCH  FOR  BREEDING  PLACES 

In  a  general  way  the  character  of  the  breeding  places 
of  flies  has  been  described  in  Chapter  I,  and  the  state- 


PREVENTIVE  MEASURES  191 

ment  is  there  made  that  they  will  breed  in  almost  any 
fermenting  organic  material.  They  prefer  horse  ma- 
nure, but  will  breed  in  human  excreta,  in  cow  dung, 
and  the  dung  of  pigs,  fowls,  and  other  animals,  in  fer- 
menting spent  hops,  bran,  in  ash  barrels  containing 
more  or  less  organic  matter,  and  in  everything  of  the 
sort.  Search  must  therefore  be  made  for  every  ac- 
cumulation of  refuse  of  this  kind  within  a  large  radius. 
To  gain  the  requisite  conditions  for  fermentation,  it  is 
necessary  as  a  rule  for  the  substances  in  which  flies 
will  breed  to  accumulate  until  a  considerable  quantity 
is  reached,  at  least  such  an  amount  as  will  be  readily 
noticeable;  so  that  the  search  for  the  breeding  places 
of  the  bulk  of  the  flies  of  a  given  neighborhood  need 
not  be  a  very  close  one. 

The  question  arises,  however :  In  how  small  an 
amount  of  breeding  material  will  fly  larvae  be  found  ? 
Certain  breeding  materials  will  remain  moist  in  small 
quantity  longer  than  others;  a  single  dropping  from 
a  cow  is  very  liquid,  but  it  hardens  so  rapidly  on  top 
and  its  exterior  becomes  so  tough  that  the  house  fly 
seems  to  find  difficulty  in  issuing  from  it,  and  perhaps 
that  is  one  of  the  reasons  why  this  substance  is  not  a 
more  prolific  breeding  place  for  this  species  than  it  is; 
though  certain  other  flies,  such  as  the  horn  fly  of  cattle, 
breed  in  cow  dung  in  great  numbers. 

Horse  dung  is  so  mixed  with  the  materials  which 
have  been  eaten  that  it  dries  very  quickly  indeed  all 
through  the  mass ;  so  that  a  single  dropping  of  a  horse 
in  a  pasture  under  ordinary  summer  conditions  will 


192    THE  HOUSE  FLY— DISEASE  CARRIER 

dry  so  quickly  from  top  to  bottom  that,  although  flies 
may  and  do  lay  their  eggs  on  it,  the  larvae  are  for  the 
most  part  destroyed  by  the  drying.  When  the  weather 
is  at  all  moist,  however,  these  individual  horse  drop- 
pings will  give  out  their  supply  of  flies.  Again,  if  the 
drying  of  the  manure  is  delayed  only  until  the  larvae 
have  reached  a  certain  size,  they  will  still  be  able  to 
transform.  An  experiment  made  by  Hine  in  this  direc- 
tion is  of  interest  as  showing  the  vitality  of  larvae 
under  adverse  conditions.  Several  glass  jars  were 
partly  filled  with  thoroughly  air-dried  horse  manure; 
then  from  a  manure  pile  larvae  of  different  sizes  were 
procured,  sorted,  and  put  into  the  jars;  flies  issued  in 
every  case,  but  those  from  the  larvae  that  were  small- 
est when  sorted  out  were  not  more  than  half  normal 
size.  This  suggests  that  larvae  do  not  have  to  be  very 
large  before  they  are  in  position  to  contend  with  ad- 
verse conditions  and  produce  adults  even  when  the 
food  supply  is  shut  off,  since  it  seems  reasonably  cer- 
tain that  larvae  will  not  feed  upon  perfectly  dry  sub- 
stances. 

As  to  human  excreta,  observations  have  shown  that 
single  droppings  in  the  field  or  elsewhere  will  support 
a  generation  of  flies  perfectly.  In  Washington  in  the 
summer  of  1900  this  was  proved  on  numerous  occa- 
sions during  June  and  July. 

The  possibility  of  fly  breeding  from  spread  manure 
is  another  important  and  very  practical  point.  Hine's 
unpublished  observations  on  this  point  are  interesting. 
Cages  covering  twenty-five  square  feet  of  surface  were 


PREVENTIVE  MEASURES  193 

constructed,  and  horse  manure  infested  with  larvae  was 
spread  at  the  rate  of  one  quart  to  a  square  foot.  Flies 
came  out  in  abundance  in  these  cages,  although  the 
weather  was  such  that  the  manure  and  the  soil  beneath 
it  were  very  dry  during  the  time  the  observations  were 
taken.  After  the  flies  from  the  larvae  that  were  in  the 
manure  at  the  time  it  was  spread  out  all  emerged,  the 
cages  were  kept  in  place  for  several  weeks,  but  another 
generation  of  flies  did  not  appear,  indicating  that  the 
careful  spreading  of  manure  in  the  fields  in  the  sum- 
mer does  not  cause  the  death  of  the  pupae  and  of  the 
majority  of  the  larvae  that  are  in  it  at  the  time  the 
spreading  is  done,  but  it  does,  on  the  other  hand,  pre- 
vent the  development  of  future  generations  in  this  same 
manure. 

Thus  it  often  happens  that  after  a  lawn  has  been 
heavily  manured  in  early  summer  the  occupants  of  the 
house  will  be  pestered  with  flies  for  a  time,  but  finding 
no  available  breeding  places  these  disappear  sooner  or 
later.  Another  generation  will  not  breed  in  the  spread 
manure. 

In  the  search  for  breeding  places  no  accumulations 
of  rubbish  of  any  kind  must  be  ignored.  Even  old 
rags  and  paper  under  proper  moisture  conditions  will 
afford  breeding  places.  All  such  substances  should  be 
removed  or  destroyed. 

THE  TREATMENT  OF  HORSE  MANURE 

Some  experiments  were  tried  by  the  writer  in  the 
summer  of  1897,  with  the  intention  of  showing 


194    THE  HOUSE  FLY— DISEASE  CARRIER 

whether  it  would  be  possible  to  treat  a  manure  pile  in 
such  a  way  as  to  stop  the  breeding  of  flies.  Previous 
experience  with  the  use  of  air-slaked  lime  on  cow 
manure  to  prevent  the  breeding  of  the  horn  fly  sug- 
gested the  experimentation  with  different  lime  com- 
pounds. It  was  found  to  be  perfectly  impracticable 
to  use  air-slaked  lime,  land  plaster,  or  gas  lime  with 
good  results.  Few  or  no  larvse  were  killed  by  a  thor- 
ough mixture  of  the  manure  with  any  of  these  sub- 
stances. 

Chloride  of  lime,  however,  was  found  to  be  an  ex- 
cellent maggot-killer.  Where  one  pound  of  chloride 
of  lime  was  mixed  with  eight  quarts  of  horse  manure, 
ninety  per  cent,  of  the  maggots  were  killed  in  less  than 
twenty-four  hours.  At  the  rate  of  a  quarter  of  a  pound 
of  chloride  of  lime  to  eight  quarts  of  manure,  however, 
the  substance  was  not  sufficiently  strong.  Chloride  of 
lime,  although  cheap  in  Europe,  costs  at  least  three  and 
one-half  cents  a  pound  in  large  quantities  in  this  coun- 
try, so  that  frequent  treatment  of  a  large  manure  pile 
with  this  substance  would  be  out  of  the  question  in  ac- 
tual practice.  Moreover,  if  the  manure  receptacle  is  in 
the  stable  where  horses  are  kept,  or  in  close  proximity 
to  it,  the  chlorine  fumes  arising  from  a  pile  thus  treated 
would  be  an  irritant  to  the  eyes  of  the  live  stock. 

After  these  experiments  with  lime,  kerosene  was 
used.  It  was  found  that  eight  quarts  of  fresh  horse 
manure  sprayed  with  one  pint  of  kerosene  which  was 
afterwards  washed  down  with  one  quart  of  water  was 
thoroughly  rid  of  living  maggots — every  individual 


PREVENTIVE  MEASURES  195 

was  killed  by  the  treatment.  This  experiment  and 
others  of  a  similar  nature  on  a  small  scale  were  satis- 
factory. Practical  work  during  the  summer  of  1898, 
however,  demonstrated  that  on  a  large  scale  this  sub- 
stance cannot  be  used  to  good  effect.  A  large  manure 
pile  containing  the  accumulations  of  a  week  or  ten  days 
or  two  weeks  arid  coming  from  a  stable  in  which  four 
horses  were  kept  was  sprinkled  thoroughly  with  kero- 
sene and  an  attempt  was  made  to  wash  the  kerosene 
down  to  a  certain  extent  with  water.  The  experiment 
was  begun  early  in  April  and  was  carried  on  for  some 
weeks.  While  undoubtedly  hundreds  of  flies  were  de- 
stroyed in  the  course  of  this  work,  it  was  found  by  the 
end  of  May  that  it  was  far  from  perfect,  since  if  used 
at  an  economical  rate  the  kerosene  could  not  be  made 
to  penetrate  through  the  whole  pile  of  manure.  A  con- 
siderable proportion  of  larvae  escaped  injury  from  this 
treatment,  which  at  the  same  time  was  found  to  be  very 
laborious.  It  was  a  measure,  in  fact,  which  almost  no 
one  could  be  induced  to  adopt  practically. 

The  actual  experiments  indicated  the  following  facts : 

Eight  quarts  of  fresh  horse  manure  alive  with  mag- 
gots were  mixed  August  5th  with  two  quarts  of  air- 
slaked  lime.  August  7th  no  larvae  were  dead,  and  on 
August  Qth  very  many  had  hardened  into  puparia. 

August  6th,  eight  quarts  of  horse  manure  were  thor- 
oughly mixed  with  two  quarts  of  gypsum  or  land  plas- 
ter. No  larvae  were  dead  three  days  later. 

August  7th,  eight  quarts  of  horse  manure  alive  with 
larvae  were  thoroughly  mixed  with  two  quarts  of  gas 


196    THE  HOUSE  FLY— DISEASE  CARRIER 

lime  and  spread  out  in  a  large  tin  pan.  Two  days  later 
most  of  the  larvae  were  found  to  have  hardened  into 
puparia,  but  none  was  killed. 

September  4th,  eight  quarts  of  fresh  horse  manure 
containing  larvae  were  spread  out  in  a  tin  pan  and 
sprayed  with  one  pint  of  kerosene  washed  down  with 
one  quart  of  water.  September  7th,  three  days  later, 
twenty  per  cent,  of  the  larvae  were  still  living. 

September  7th,  eight  quarts  of  fresh  horse  manure 
containing  house  fly  larvae  were  placed  in  a  tin  pan, 
sprayed  with  one  pint  of  kerosene,  washed  down  after- 
wards with  one  quart  of  water.  The  manure  was  then 
mixed  and  a  little  more  water  poured  on.  Twenty-four 
hours  later  every  larva  in  the  mass  was  dead. 

October  I5th,  one  pound  of  chloride  of  lime  was 
mixed  with  eight  quarts  of  well-infested  horse  manure, 
which  was  kept  in  a  bucket.  October  i6th,  ninety  per 
cent,  of  the  larvae  were  dead,  the  remainder  having 
burrowed  into  the  large  lumps  of  manure.  October 
1 8th,  no  living  larvae  could  be  found. 

October  2ist,  one-quarter  of  a  pound  of  chloride  of 
lime  was  mixed  with  eight  quarts  of  fresh  horse  ma- 
nure and  kept  in  a  bucket.  This  treatment  was  unsuc- 
cessful and  only  two  larvae  were  killed. 

Herms  also  conducted  certain  experiments  in  this 
direction  at  the  University  of  California.  He  found 
that  the  fly  larvae  are  extremely  tenacious  of  life,  and 
that  insecticides  which  will  kill  them  must  be  strong, 
in  fact  from  two  to  five  times  as  strong  as  those  which 
are  useful  against  other  insects.  He  writes,  "Chem- 


PREVENTIVE  MEASURES  197 

icals  used  to  destroy  the  larvae  in  the  manure  pile  may 
be  roughly  divided  into  two  classes :  ( i )  Contact  poi- 
sons, and  (2)  stomach  poisons.  To  the  first  class  be- 
long such  preparations  as  the  kerosenes  (generally 
used  in  the  form  of  emulsions)  and  the  creosol  prepa- 
rations, also  chloride  of  lime.  To  the  second  class  be- 
long the  arsenicals,  represented  by  arsenate  of  lead  and 
Paris  green.  All  of  these  insecticides  are  more  or  less 
effective  when  used  in  proper  concentrations  and  in 
sufficient  quantities,  but  none  of  them  can  be  applied 
with  any  degree  of  safety  to  man  or  to  the  domesticated 
animals  because  of  either  their  inflammable,  poisonous, 
or  corrosive  nature." 

Prof.  S.  A.  Forbes,  of  Illinois,  also  caused  a  series 
of  experiments  of  this  sort  to  be  carried  on  at  the  Illi- 
nois State  Experiment  Station  at  Urbana.  The  work 
was  done  under  his  direction  by  Mr.  J.  J.  Davis.  The 
notes  have  not  been  published,  but  have  been  kindly 
sent  to  the  writer  by  Professor  Forbes.  In  these  ex- 
periments it  was  found  that  three  pounds  of  hydrated 
high  calcium  lime  of  the  Marblehead  Lime  Company, 
mixed  with  fifteen  pounds  of  horse  manure,  killed 
ninety-four  per  cent,  of  the  larvse;  two  pounds  mixed 
with  twelve  pounds  of  manure  killed  sixty-nine  and 
one-tenth  per  cent,  of  the  larvse;  four  pounds  with 
twelve  pounds  of  manure  killed  sixty-one  and  three- 
tenths  per  cent.  The  diminished  percentage  in  the 
last  two  experiments  is  accounted  for  by  the  fact  that 
the  larvse  were  nearly  full-grown. 

An  experiment  with  two  pounds  of  iron  sulphate 


198    THE  HOUSE  FLY— DISEASE  CARRIER 

dissolved  in  a  gallon  of  water  and  poured  upon  fifteen 
pounds  of  horse  manure  showed  that  941  out  of  every 
1,000  larvae,  or  ninety-four  and  one-tenth  per  cent., 
were  killed,  while  the  same  amount  poured  upon  twelve 
pounds  of  horse  manure  killed  ninety-five  and  seven- 
tenths  per  cent,  of  the  larvae.  Other  experiments  with 
the  same  substance  indicated  in  one  case  that  two  and 
one-half  pounds  of  the  iron  sulphate  to  the  gallon  of 
water  poured  on  twelve  pounds  of  manure  killed  but 
seventy-one  per  cent,  of  the  larvae ;  in  still  another,  two 
pounds  of  the  sulphate  and  two  gallons  of  water  poured 
upon  fifteen  pounds  of  manure  killed  eighty-three  and 
five-tenths  per  cent.,  while  one  gallon  of  the  same  solu- 
tion to  eleven  pounds  of  manure  killed  none.  Experi- 
menting with  dry  powdered  iron  sulphate  mixed  with 
horse  manure  at  the  rate  of  two  and  one-half  pounds 
to  the  fifteen,  he  found  eighty-seven  and  two-tenths 
per  cent,  of  the  larvae  destroyed.  At  the  rate  of  two 
and  three-eighths  pounds  to  twelve,  eighty-six  per  cent, 
were  killed.  At  two  pounds  to  fifteen,  forty-four  and 
three-tenths  per  cent,  were  destroyed.  At  the  rate  of 
one  and  one-half  pounds  to  twelve,  sixty-nine  and 
seven-tenths  per  cent,  were  killed. 

The  conclusions  drawn  from  these  experiments  were 
that  the  breeding  of  the  house  fly  in  manure  can  be 
controlled  by  the  application  of  a  solution  of  iron  sul- 
phate— two  pounds  in  a  gallon  of  water  for  each  horse 
per  day — or  by  the  use  o'f  two  and  one-half  pounds  of 
dry  sulphate  per  horse  per  day.  It  was  calculated  that 
the  average  city  horse  produces  about  fifteen  pounds 


PREVENTIVE  MEASURES  199 

of  manure  daily ;  the^ larger  work  horses  produce  twenty 
to  thirty  pounds  per  day,  but,  as  they  are  out  of  the 
stables  most  of  the  time,  the  actual  amount  to  be  treated 
would  be  much  less.  The  average  cost  of  the  treat- 
ment would  be  one  and  one-half  to  two  cents  per  horse 
per  day.  It  is  stated  also  that  iron  sulphate  has  the  ad- 
vantage that  it  completely  deodorizes  the  manure. 

Experiments  were  also  made  under  Forbes's  direc- 
tion with  borax,  with  a  mixture  of  sodium  arsenate  and 
borax,  with  a  lime-sulphur  solution,  with  salt,  and  with 
carbon  bisulphid.  It  was  found  that  a  solution  of  thir- 
teen ounces  of  borax  to  three- fourths  of  a  gallon  of 
water  sprayed  over  fifteen  pounds  of  infested  manure 
destroyed  over  ninety-nine  per  cent,  of  the  maggots.  A 
gallon  of  water  containing  eleven  and  one-half  ounces 
of  borax  and  seven  ounces  of  sodium  arsenate  applied 
to  twelve  pounds  of  manure  killed  all  of  the  larvae.  A 
pint  of  lime-sulphur  solution  in  a  gallon  of  water  ap- 
plied to  twelve  pounds  of  manure  killed  eighty-six  and 
four-tenths  per  cent,  of  the  larvae,  while  a  pound  and 
a  half  of  salt  to  one  gallon  of  water  applied  to  twelve 
pounds  of  manure  killed  eighty-eight  ~and  eight-tenths 
per  cent. 

A  fluid  ounce  of  bisulphid  of  carbon  evaporated  in  a 
closed  box  fourteen  inches  by  fourteen  inches  by  nine 
inches,  containing  twelve  pounds  of  manure,  destroyed 
ninety-nine  per  cent,  of  the  larvae. 

Whenever  the  subject  of  treating  manure,  in  order 
to  kill  the  maggots  which  are  living  in  it,  is  mentioned, 
the  question  arises :  What  effect  will  the  treatment  have 


200    THE  HOUSE  FLY— DISEASE  CARRIER 

upon  the  manure  itself?  Will  it  destroy  its  qualities 
and  render  it  less  valuable  as  a  fertilizer?  The  ideal 
treatment  would  be  to  kill  the  fly  larvae  and  make  the 
manure  more  valuable,  if  that  were  possible.  Finding 
that  the  use  of  iron  sulphate  seemed  practical,  as  just 
pointed  out,  Forbes  consulted  a  competent  chemist,  and 
received  a  reply  from  which  he  quotes  as  follows  in  a 
letter  recently  received  by  the  writer: 

"A  great  deal  of  work  has  been  done  by  German 
and  French  investigators  in  using  sulphate  of  iron  as 
a  fertilizer.  On  going  over  this  work  carefully,  we 
cannot  find  that  sulphate  of  iron  has  ever  proven  in- 
jurious to  the  soil.  On  the  contrary,  its  use  gave  very 
beneficial  results  in  practically  all  cases.  When  sul- 
phate of  iron  is  added  to  manure  it  will  rarely,  if  ever, 
reach  the  soil;  this  for  the  reason  that  it  will  be  con- 
verted either  into  ammonium  iron  compounds  or  de- 
composed into  its  elements.  We  have  used  as  high  as 
one  hundred  pounds  of  sulphate  of  iron  to  one  square 
rod  without  rendering  the  ground  sterile.'* 

Professor  Forbes  goes  on  to  state  that  his  corre- 
spondent added  that  sulphate  of  iron  is  now  being  used 
in  Florida  by  some  of  the  most  progressive  orange 
growers  and  that  very  many  carloads  of  it  \vere  shipped 
into  that  State  during  the  summer  of  1916.  Further, 
that  the  orange  growers  of  California  are  also  buying 
it  in  large  quantities.  His  correspondent  concludes  by 
stating  that  the  small  amount  of  sulphate  of  iron  neces- 
sary for  the  extermination  of  flies  will  not  have  a  dele- 
terious effect  upon  the  soil. 


PREVENTIVE  MEASURES  201 

Dr.  H.  W.  Wiley,  the  Chief  Chemist  of  the  U.  S. 
Department  of  Agriculture,  was  asked  for  an  opinion 
regarding  the  effect  upon  the  manurial  value  of  manure 
treated  by  the  substances  experimented  with  under  Pro- 
fessor Forbes's  direction.  He  replied,  "The  materials 
which  you  mention  would  affect  the  agricultural  value 
of  manure  in  three  ways :  Alkalies  would  drive  off  am- 
monia, and  if  in  not  too  large  quantities,  would  hasten 
fermentation.  Lime  salts  and  iron  sulphate  would 
tend  to  render  the  phosphates  unavailable.  All  of  these 
materials  mentioned,  with  the  possible  exception  of 
salt,  would,  if  used  in  sufficient  quantity,  kill  the  bac- 
teria of  the  manure  and  thus  reduce  its  value,  as  un- 
doubtedly the  value  of  stable  manure  is  largely  due  to 
the  great  number  of  very  active  bacteria  which  it  con- 
tains. I  cannot  inform  you  in  what  quantities  these 
various  materials  would  be  required  to  seriously  re- 
duce the  bacterial  content  of  manure,  but  it  would  seem 
that,  if  used  in  sufficient  quantity  to  kill  larvae,  they 
would  have  a  decided  effect  on  the  bacterial  life  of  the 
manure.^ 

REMOVAL  OF  MANURE  AND  RECEPTACLES  FOR  ITS 
TEMPORARY  STORAGE 

The  average  time  elapsing  between  the  laying  of  the 
eggs  and  the  issuing  of  the  adult  flies,  as  we  have  seen, 
is,  in  midsummer  in  the  climate  of  Washington,  about 
ten  days.  In  warmer  regions,  and  with  plenty  of  mois- 
ture, it  may  be  as  short  as  eight  days.  Therefore  it  is 
by  all  means  advisable  to  have  manure  accumulations 


202    THE  HOUSE  FLY— DISEASE  CARRIER 

removed  at  least  once  a  week,  although  from  all  points 
of  view  aside  from  that  of  convenience  a  removal  and 
spreading  every  day  would  be  better. 

The  writer  has  for  some  years  advised  that  stables 
should  be  fitted  with  fly-tight  pits  or  closets  into  which 
the  daily  manure  may  be  shoveled,  and  which  at  the 
same  time  should  be  arranged  conveniently  for  taking 
the  manure  away  at  intervals  of  a  week.  In  his  first 
experiment  with  the  old  stables  of  the  U.  S.  Depart- 
ment of  Agriculture  he  utilized  a  corner  closet  with 
a  door  opening  into  the  stable.  An  outside  door  was 
cut  through  the  wall,  and  the  place  was  ventilated  with 
screened  apertures.  The  daily  manure  was  shoveled 
in,  and  conveniently  removed  into  carts,  through  the 
outside  door  at  the  week  end.  And  at  a  large  country 
club,  during  the  summer  of  1910,  he  advised  the  build- 
ing of  a  manure  pit  in  a  convenient  side  hill ;  the  top 
of  the  pit  being  near  the  stable  and  at  a  much  higher 
elevation  than  the  other  end  of  the  pit,  which  was  so 
situated,  that  a  cart  could  be  driven  before  it,  the  door 
opened,  and  the  manure  readily  shoveled  out. 

The  regulations  of  the  District  of  Columbia  provide 
simply  for  a  covered  receptacle,  and  it  has  been  found 
that  a  tight-covered  barrel  answers  the  purpose  for  a 
one-horse  stable. 

In  Berkeley,  California,  according  to  Herms  (1910), 
at  such  stables  a  simple  galvanized  iron-garbage  can 
has  been  found  very  useful  and  convenient,  or  even  a 
tight  barrel  covered  with  a  tightly  fitting  lid.  In  Berk- 
eley the  contents  of  these  receptacles  are  removed  once 


PREVENTIVE  MEASURES  203 

or  twice  a  week,  either  by  the  city  scavengers,  or  by 
gardeners  for  fertilizing  purposes.  In  the  case  of  a 
large  stable,  where  many  horses  are  cared  for,  Herms 
recommends  such  a  closet  as  was  used  in  Washington, 
or  the  construction  of  a  lean-to  or  shed  connecting  with 
the  stable  by  means  of  a  small  screened  door.  Where 
it  is  not  convenient  to  construct  a  lean-to  because  of 
sliding  doors  or  other  obstructions,  he  recommends  a 
large  bin,  either  of  wood  or  of  concrete,  with  a  hinged 
top.  He  illustrates  a  type  of  concrete  bin  used  in  one 
of  the  fire-engine  houses  in  Berkeley,  but  shows  that 
it  is  not  conveniently  constructed,  since  it  is  unhandy 
to  remove  the  manure.  It  ought  not  to  be  difficult  to 
construct  a  concrete  bin  with  a  lidded  top,  and  a  lower 
hinged  door  from  which  the  manure  can  be  removed 
conveniently. 

THE  SANITARY  PRIVY 

The  uncared-for  privy,  both  on  farms  and  in  towns, 
will  eventually  disappear,  and  the  sooner  it  goes  the 
better  it  will  be  for  human  health.  It  is  a  prolific 
source  of  soil  contamination  and  a  prolific  breeder  of 
germ-laden  flies.  Who  can  estimate  the  number  of 
lives  that  have  been  lost  through  the  persistence  of  this 
primitive  and  persistent  blot  upon  conditions  of  life 
which  might  otherwise  be  called  civilized? 

Hardly  any  one  realizes  the  extent  to  which  this 
semi-barbaric  institution  exists  in  many  parts  of  the 
country,  and  as  a  matter  of  fact  I  am  sure  that  the 
average  person  in  the  large  city  has  no  idea  of  the 


204    THE  HOUSE  FLY— DISEASE  CARRIER 

fact  that  there  are  many  comparatively  intelligent  citi- 
zens who  in  sanitary  matters  have  not  even  reached 
the  grade  of  civilization  which  demands  the  sanitary 
privy.  Stiles,  in  the  course  of  his  great  work  in  the 
Southern  States,  has  brought  together  some  startling 
figures.  He  is  responsible  for  the  statement  that  with 
4,825  American  farmhouses  in  six  different  States 
2,664,  or  fifty-five  per  cent.,  have  no  privies  of  any 
kind ;  of  2,499  houses  inhabited  by  white  people,  thirty- 
five  and  three-tenths  per  cent,  have  absolutely  none, 
and  of  2,326  inhabited  by  negroes  seventy-six  and 
eight-tenths  per  cent,  have  none.  And  what  shall  be 
said  of  the  condition  of  a  large  part — the  very  great 
majority — of  those  which  do  exist?  The  uncared-for 
privy  is  still  a  most  important  factor  all  over  the  United 
States,  even  in  portions  of  our  most  cleanly  cities. 

In  the  better  class  of  country  houses,  especially  in 
summer  country  communities  of  city  people,  efforts 
have  been  made  to  improve  this  condition  of  affairs; 
and  it  should  be  said  parenthetically  that  the  influence 
of  these  summer  country  communities  of  city  people 
upon  the  general  conditions  of  the  life  of  the  country 
people  around  them  is  of  great  and  growing  value,  for 
the  imitative  turn  of  mind  of  the  young  country  people 
is  overpowering  the  conservatism  of  the  older  indi- 
viduals. 

But  the  attempts  which  have  been  made  even  in 
some  of  these  summer  colonies  to  attack  the  privy 
question  have  not  been  at  all  satisfactory.  The  earth 
closet  has  had  a  great  vogue  and  still  remains  to  a  great 


PREVENTIVE  MEASURES  205 

extent.  Confining  ourselves  strictly  fo  the  fly  question 
and  to  no  other,  an  earth  closet  unprovided  with  a 
removable  bucket  and  from  which  the  contents  are  re- 
moved only  at  considerable  intervals  is  little  better  than 
the  uncared-for  privy,  except  that  it  is  usually  less  ac- 
cessible to  flies.  A  slight  covering  of  earth  over  the 
contents  is  no  protection  against  the  emergence  of 
adult  flies  coming  from  larvae  within  the  substance. 
It  is  not  a  protection  against  infestation  from  flies 
coming  in  from  outside,  since  these  have  been  shown 
to  lay  their  eggs  upon  the  earth  covering  excreta. 
When  the  eggs  hatch,  the  young  larvae,  being  very  ac- 
tive, soon  burrow  to  their  proper  food. 

Accurate  experiments  have  been  made  by  several 
observers  concerning  the  distance  which  the  newly 
emerged  fly  will  struggle  through  earth  to  the  air. 
Hine  (in  lit.)  experimented  with  ordinary  soil  and 
found  in  a  single  experiment  that  adults  were  not  able 
to  emerge  from  a  depth  of  six  inches,  but  Stiles  and 
Gardner,  of  the  U.  S.  Public  Health  and  Marine-Hos- 
pital Service,  have  shown  that,  in  experiments  with 
sterilized  sand,  house  flies  to  the  number  of  thirty- 
seven,  issuing  from  fecal  material  buried  in  a  screened 
standpipe  under  forty-eight  inches  of  sand,  came  to 
the  surface.  Some  of  these  flies  were  sent  to  the 
writer's  office  for  determination  and  were  named  by 
Mr.  Coquillett.  They  were  in  a  somewhat  damaged 
condition,  clue  probably  to  their  long  struggle  for  free- 
dom. In  the  same  series  of  experiments,  other  flies  of 
undetermined  genus  and  species  struggled  up  to  free- 


206    THE  HOUSE  FLY— DISEASE  CARRIER 

dom  through  seventy-two  inches  of  sterilized  sand, 
truly  an  heroic  struggle! 

Dry  earth,  therefore,  is  not  satisfactory,  although  in 
earth  closets  provided  with  buckets  removed  daily  the 
problem  resolves  itself  into  the  question  of  the  proper 
disposal  of  the  contents  of  the  buckets. 

In  many  localities  lime  is  used  instead  of  dry  earth. 
A  careful  study  of  the  lime  system  was  made  by  Stiles 
and  Gardner  in  a  certain  industrial  village  of  the  South. 
In  that  village  the  habit  was  to  clean  the  outhouses 
once  a  week  and  to  distribute  the  lime  free  to  the  fam- 
ilies. The  people  were  notified  repeatedly  that  the  lime 
should  be  used  regularly  and  generously,  and  the  au- 
thorities of  the  village  assured  the  observers  that  all 
reasonable  efforts  were  made  to  carry  out  the  system 
properly.  It  therefore  seemed  to  the  Government  men 
that  this  particular  village  was  a  very  fair  case  to  take 
as  a  basis  for  observations  as  to  the  actual  workings  of 
the  system.  Their  observations  were  careful,  and  they 
found  that  in  thirty-two  instances  out  of  eighty-eight 
the  lime  had  actually  been  used,  and  the  conclusion  was 
that,  even  where  lime  is  furnished  free  of  cost  and  the 
people  are  urged  to  use  it,  it  is  not  generally  adopted. 
Moreover,  of  the  thirty-two  outhouses  in  which  it  had 
been  used,  it  was  freely  used  in  only  three  cases. 

The  conclusion  was  that  families  cannot  be  relied 
upon  to  use  it  properly.  In  not  one  instance  of  the 
eighty-eight  did  they  fail  to  find  exposed  night-soil  of 
easy  access  to  flies  and  other  insects.  Live  fly  larvae 
were  found  in  all  samples  taken.  It  may  be  mentioned 


PREVENTIVE  MEASURES  207 

also,  incidentally,  that  live  hookworm  eggs  were  also 
found.  Interesting  observations  were  made  upon  the 
practical  workings  of  the  cleaning  process,  which  need 
not  be  detailed  except  to  state  briefly  that  the  process 
of  cleaning  was  by  no  means  perfect,  and  that  in  carry- 
ing the  cartloads  away  flies  and  possibly  contaminated 
flies  were  distributed  here  and  there  and  everywhere, 
while  the  dump  was  inhabited  by  swarms. 

The  lime  system,  therefore,  is  a  failure,  even  if -one 
can  rely  upon  its  proper  administration,  and  it  is  not 
only  a  failure,  as  pointed  out  by  Gardner  and  Stiles, 
but  it  is  an  additional  menace  from  the  feeling  of  false 
security  which  it  gives  to  the  persons  who  use  it. 

It  seems,  as  a  result  of  the  experimental  work  car- 
ried on  by  the  observers  mentioned  above,  that  surface 
privies  should  without  further  delay  be  remodeled  into 
a  tub,  pail,  or  barrel  system,  and  that  water  or  kero- 
sene and  water  should  be  used  to  kill  fly  larvae  or  hook- 
worm eggs  or  other  dangerous  forms  found  in  excreta. 
Their  experiments  indicate  that  a  mixture  of  crude 
carbolic  acid  and  water  will  kill  the  fly  larvse,  but  on 
account  of  the  dangers  in  the  use  of  this  mixture  they 
do  not  recommend  it.  Water  only,  placed  in  the  bucket, 
is  not  recommended,  since  not  only  may  live  eggs  of 
the  hookworm  be  found  in  the  water  at  the  end  of 
twenty-four  hours,  but  mosquitoes  will  lay  their  eggs 
in  the  buckets  and  breed  there.  A  film  of  kerosene 
on  the  surface  of  water  kills  everything,  including 
hookworm  eggs,  round-worm  eggs,  fly  larvse,  and  mos- 
quito larvae.  The  principal  objection  to  the  use  of 


208    THE  HOUSE  FLY— DISEASE  CARRIER 

water  with  a  film  of  kerosene  on  top  in  an  ordinary 
unprotected  tub.  pail,  or  barrel  system  is  that  if  the 
water  is  too  deep  splashing  occurs,  and  a  wet  system 
calls  for  a  large  receptacle. 

In  a  recent  publication,  Stiles  (1910)  covers  the  whole 
subject,  and  gives  directions  for  building  a  really  sani- 
tary privy,  indicating  that  any  fourteen-year-old  school- 
boy of  average  intelligence  in  mechanical  engineering 
could,  by  following  the  plans  given,  build  a  sanitary 
privy  for  his  home  at  an  expense  for  building  materials, 
exclusive  of  receptacle,  of  from  five  to  ten  dollars,  ac- 
cording to  locality.  The  plan  (directions  for  its  con- 
struction are  printed  as  Appendix  IV)  provides  for  a 
fly-proof  structure,  well  ventilated,  with  a  receptacle 
for  the  excreta  mounted  on  a  floor  and  protected  from 
behind  by  a  hinged  door  through  which  it  can  be  re- 
moved. The  receptacle  always  contains  the  necessary 
amount  of  water  with  a  film  of  kerosene  floating  on  it. 
The  most  casual  observation  will  indicate  when  to  re- 
new the  water  and  kerosene  and  when  to  empty  the 
receptacle. 

Since  the  publication  of  the  bulletin  in  question, 
Lumsden,  Roberts,  and  Stiles,  of  the  Public  Health 
Service,  have  devised  an  additional  arrangement  which 
they  have  had  in  constant  use  in  the  Hygienic  Labora- 
tory at  Washington  for  several  months.  Concerning 
the  practical  workings  of  this  apparatus  they  seem 
very  enthusiastic.  The  writer  himself  has  visited  it 
and  found  it  perfectly  unobjectionable  after  being  in 
use  for  moVe  than  three  months  without  having  been 


PREVENTIVE  MEASURES  209 

once  emptied.  A  description  of  the  apparatus  with  a 
diagram  of  its  construction  will  be  found  in  Appendix 
V.  Its  cost  of  construction  is  said  to  be  about  $1.40, 

There  seems  no  doubt  that  this  invention  of  the  of- 
ficers of  the  Public  Health  and  Marine-Hospital  Ser- 
vice is  the  best  down  to  the  present  time  in  the  way 
of  a  sanitary  privy.  Recommendations,  however,  have 
been  made  in  this  direction  by  boards  of  health  and  by 
private  individuals.  Rev.  George  W.  Lay  (1910),  for 
example,  has  given  at  considerable  length  directions 
for  the  construction  of  a  good  privy,  and  terms  it  "The 
North  Carolina  Sanitary  Privy."  He  rather  holds  to 
the  dry-earth  view,  and  mentions  kerosene  only  by 
stating  that  if  a  little  of  it  is  sprinkled  in  the  privy  box 
it  will  have  a  tendency  to  keep  the  flies  away. 

Kerosene,  however,  should  be  used,  not  so  much  as 
a  preventive,  but  as  a  means  of  destroying  eggs  and 
larvae.  In  communities  like  mill  towns,  where  the  ma- 
jority of  the  flies  breed  in  the  privies  owing  to  the  lack 
of  horse  stables  and  horse  manure,  and  it  may  be 
found  impossible  to  compel  the  construction  of  new 
sheds,  the  use  of  kerosene  on  the  dejecta  will  be  ef- 
fective. 

In  1906,  the  Paris  journal  Le  Matin  offered  a  prize 
for  the  best  methods  of  destroying  flies.  The  compe- 
tition attracted  a  great  deal  of  attention,  which  was 
fostered  by  the  newspaper  by  frequent  articles.  The 
prize  was  finally  awarded  to  an  anonymous  writer  who 
proposed  to  pour  green  oil  of  schiste  in  privies  and 
upon  manure  piles,  mixing  it  in  the  latter  case  with 


210    THE  HOUSE  FLY— DISEASE  CARRIER 

earth  or  lime.  The  oil  of  schiste  is  a  crude  petroleum 
found  in  Europe.  In  the  number  of  July  19,  1907, 
the  paper  stated  that  this  proceeding  had  given  excel- 
lent results  and  that  flies  had  disappeared  wherever  it 
had  been  applied.  At  the  International  Congress  of 
Hygiene  in  Berlin  following.  Professor  Bordas  con- 
firmed the  statements  of  Le  Matin,  and  added  that  the 
Governor  of  Kiaotscheau  had  obtained  excellent  re- 
sults by  the  oil  method.  Galli-Valerio  (1910),  being 
greatly  interested  in  this  matter,  wrote  to  Doctor  Dirk- 
sen,  physician  to  the  Government  at  Tsingtau,  and 
found  out  that  only  five  liters  of  the  oil  of  schiste  were 
sent  to  the  Governor  by  Le  Mat  hi,  and  thinks  that  the 
results  of  work  on  such  a  small  scale  are  not  at  all  con- 
vincing. Experiments  made  by  the  writer,  however, 
with  the  use  of  kerosene  upon  horse  manure,  convince 
him  that  it  will  act  equally  well  in  privies,  and  in  this 
statement  he  has  the  endorsement  of  Stiles  and  others. 

A  Compulsory  Sanitary  Privy  Law 

The  following  paragraphs,  quoted  from  Stiles 
(1910),  excellently  express  some  very  sound  ideas  on 
this  subject. 

"A  compulsory  sanitary  privy  law  or  ordinance 
should  exist  and  be  strictly  enforced  in  all  localities  in 
which  connection  with  a  sewer  system  is  not  enforced. 

"Since,  from  a  sanitary,  point 'of  view,  the  privy  is 
a  public  structure  in  that  it  influences  public  health,  it 
seems  wisest  to  have  city  and  town  ordinances  which 
provide  for  a  licensing  of  all  privies,  the  license  being 


PREVENTIVE  MEASURES 

fixed  at  a  sum  which  will  enable  the  city  or  town  to 
provide  the  receptacles  (tub,  pail,  etc.),  the  disinfectant, 
and  the  service  for  cleaning.  The  expense  involved 
will  vary  according  to  local  conditions,  such  as  cost 
of  labor  and  density  of  population.  If  the  "chain  gang" 
can  be  utilized  for  cleaning,  the  expense  for  labor  is 
reduced. 

'The  importance  of  taking  the  responsibility  for  the 
care  of  the  privy  out  of  the  hands  of  the  family  is 
evident  when  one  considers  that  one  careless  family 
in  ten  or  in  a  hundred  might  be  a  menace  to  all.  The 
removal  of  garbage  and  of  ashes  is  recognized  as  a 
function  of  the  city  or  town  in  all  better-organized  com- 
munities, and  the  idea  is  constantly  spreading  that  this 
service  should  extend  to  a  removal  of  the  night-soil 
also. 

"In  correspondence  with  certain  cotton  mills,  esti- 
mates for  privy  cleaning  (once  a  week)  vary  from 
about  twenty  to  twenty-five  cents  per  privy  per  month. 
A  privy  tax  of  $3.50  to  $5  per  privy  per  year  ought 
to  give  satisfactory  service,  including  receptacle,  but 
the  exact  amount  of  the  tax  must  be  determined  by 
experience  in  each  locality. 

"It  is  probably  the  exception  that  an  economical  pub- 
lic privy-cleaning  service  can  be  carried  out  in  the  open 
country,  on  account  of  the  distances  between  the 
houses.  To  meet  the  difficulties  involved,  several  sug- 
gestions may  be  considered,  according  to  conditions : 

"A  country  privy  tax  can  be  levied,  the  county  can 
furnish  the  pail  and  the  disinfectant,  and  ( i )  one  mem- 


THE  HOUSE  FLY— DISEASE  CARRIER 

her  of  each  family  or  of  several  neighboring  families 
hired  to  clean  the  privy  regularly;  or  (2)  the  landlord 
can  be  held  responsible  for  the  cleaning  of  all  privies 
of  his  tenants,  receiving  from  the  county  a  certain  sum 
for  the  service:  or  (3)  "trusties"  from  prisons  might 
possibly  be  utilized  in  some  districts  not  too  sparsely 
settled;  or  (4)  a  portion  of  the  county  privy  tax  might 
perhaps  be  apportioned  by  school  districts  and  be  dis- 
tributed as  prizes  among  the  school  boys  who  keep 
their  family  privies  in  best  condition;  or  (5)  each 
head  of  family  might  be  held  responsible  for  any  soil 
pollution  that  may  occur  on  his  premises  and  be  fined 
therefor. 

"Undoubtedly  the  problem  of  the  privy  cleaning  in 
the  open  country  is  much  more  difficult  than  in  cities, 
villages,  and  towns,  and  in  the  last  instance  involves 
a  general  education  of  the  rising  generation  of  school 
children,  more  particularly  of  the  girls  (the  future 
housekeepers),  in  respect  to  the  dangers  of  soil  pollu- 
tion." 

THE  CAPTURE  OF  ADULT  FLIES  OUTSIDE  OF  HOUSES 

Under  this  heading,  the  plan  proposed  by  Professor 
Hodge,  mentioned  in  the  introductory  paragraphs  of 
this  chapter,  must  be  considered.  His  idea,  it  will  be 
remembered,  is  to  catch  the  adult  flies  before  they  lay 
their  eggs  and  before  they  become  a  nuisance  in  houses. 
Isolated  observations  by  Dr.  C.  Gordon  Hewitt  have 
shown,  as  elsewhere  stated,  that  in  England  ten  to 
fourteen  days  elapse  after  an  adult  female  fly  issues 


PREVENTIVE  MEASURES 

before  she  lays  her  eggs,  and  it  is  during  this  period 
that  Hodge  proposes  to  catch  her. 

It  is  interesting  to  know  the  way  in  which  the  idea 
came  to  his  mind.  In  a  paper  entitled  "Extermination 
of  the  Typhoid  or  Filth  Fly,  a  Plan  of  Campaign,"  read 
before  the  annual  meeting  of  the  American  Civic  Asso- 
ciation in  Washington  in  December,  1910,  he  shows 
that  for  eight  years  previously  he  had  amused  himself 
in  the  summer  by  rearing  native  birds,  especially  the 
ruffed  grouse  and  the  bob-white.  The  enormous  quan- 
tity of  insect  food  required  by  the  young  chicks  led  him 
to  what  seemed  to  him  the  most  effective  plan  of  deal- 
ing with  the  fly  problem.  He  needed  flies  with  which 
to  feed  his  chicks,  and  the  problem  was  to  get  flies  in 
the  greatest  numbers  possible. 

Having  perfected  what  seemed  to  him  an  excellent 
method  of  accomplishing  this,  he  began  to  argue  as 
to  the  use  of  his  idea  as  a  substitute  for  the  treatment 
or  removal  of  the  manure  pile  or  the  treatment  or  re- 
moval of  all  substances  in  which  flies  will  breed.  Think- 
ing of  the  enormous  multiplication  of  the  offspring  of 
a  single  pair  in  the  springtime,  he  asks  the  pertinent 
question,  "Why  not  catch  the  original  pair  of  flies  in 
April?"  After  studying  the  problem  for  some  time, 
he  became  so  enthusiastic  over  the  prospect  that  in  his 
address  he  uses  the  following  sentence :  "If,  beginning 
next  spring,  every  family  will  adopt  effective  meas- 
ures to  kill  the  few  hundred  flies  that  succeed  in  sur- 
viving the  winter,  I  am  convinced  that  we  could  rele- 
gate our  window  screens  to  the  scrap  heap,  so  far 


THE  HOUSE  FLY— DISEASE  CARRIER 

as  our  protection  against  Musca  domestica  is  con- 
cerned." 

He  plans  certain  lines  of  attack,  all  directed  against 
the  adult  fly  out  of  doors.  The  first  of  these  lines  con- 
sists in  the  effort  to  trap  the  flies  at  their  source  of 
food  supply.  On  the  supposition  that  everything  in 
the  way  of  waste  food  which  is  attractive  to  flies  is 
or  can  be  placed  in  garbage  cans  or  swill  barrels,  he 
believes  that  a  double  wire  screen  trap  can  be  attached 
to  this  receptacle  in  such  a  way  as  to  catch  every  fly 
that  is  attracted  to  it.  He  shows  that  in  some  cities 
the  rules  of  the  boards  of  health  require  that  all  such 
receptacles  should  be  tightly  covered.  He  considers 
that  this  is  a  serious  mistake,  since  it  drives  the  flies 
from  the  garbage  into  the  kitchens.  The  garbage  cans, 
to  his  idea,  can  be  made  so  attractive  as  to  draw  the 
flies  out  of  the  kitchens  and  focus  them  at  one  spot 
and  catch  them  as  soon  as  they  come.  As  fast  as  the 
traps  are  filled,  the  contents  are  scalded  and  removed 
and  fed  to  chickens  or  put  into  the  garbage  can. 

He  has  devised  a  trap  attachment  to  garbage  cans 
with  which  on  one  occasion  he  caught  2,500  flies  in 
fifty-five  minutes.  This  was  back  of  a  market  in  an 
ice-cream  stand.  The  can  was  baited  with  fish  heads, 
meat  scraps,  watermelon  rinds  and  green  corncobs, 
over  which  the  melted  waste  from  the  ice-cream  freez- 
ers was  poured.  The  cover  of  this  can  was  held  up 
by  strips  of  metal  soldered  to  the  can  so  as  to  keep 
about  a  quarter  of  an  inch  fly  space  entirely  around 
the  can  through  which  the  flies  could  enter.  Then  a 


Fig.  20. — Fly  trap  for  garbage  cans;  designed  by  Prof.  C.  F.  Hodge. 


PREVENTIVE  MEASURES  215 

wire  gauze  trap  was  set  over  a  hole  on  the  sunny  side 
of  the  top  of  the  can.  The  flies  crawled  in,  attracted 
by  the  odor  of  food,  and  attempted  to  escape  by  the 
only  opening  through  which  the  light  came,  thus  enter- 
ing the  trap. 

Another  form  devised  by  Hodge  had  a  tight  can 
cover,  the  trap  being  contained  within  the  cover.  The 
trap  itself  forms  the  only  entrance  to  the  can,  and  the 
flies  attracted  by  the  odor  enter  the  trap.  Another 
trap  devised  was  a  wire  gauze  cylinder  fitting  over  a 
tomato  can,  the  can  being  filled  with  attractive  sub- 
stances, and  the  trap  being  arranged  so  as  to  be  scat- 
tered around  stables  or  barnyards  or  wherever  flies 
happen  to  be  congregating  or  breeding. 

He  made  still  another  arrangement  for  a  screen  for 
a  stable  cellar  or  manure  pit  window,  making  a  small 
hole  in  the  screen  near  the  top  and  providing  the  screen 
with  narrow  strips  of  tin  or  wood  to  guide  the  flies  to 
the  hole;  the  hole,  of  course,  leads  into  a  wire  gauze 
trap,  where  all  the  flies  that  emerge  will  be  caught.  In 
the  same  way  he  made  another,  also  provided  with 
guiding  strips,  on  the  outside,  and  furnished  with  a 
trap  on  the  inside,  so  as  to  catch  all  of  the  flies  that 
might  be  attracted  to  the  stable  to  lay  their  eggs.  This 
latter  idea  he  has  not  yet  tested,  but  he  argues  that 
if  the  outside  flies  were  shut  out  by  screens  they  would 
certainly  find  some  other  breeding  place  in  which  to 
lay  their  eggs. 

On  the  habit  that  flies  have  of  being  attracted  to 
kitchens  by  the  odor  of  the  cooking  or  by  the  warmth 


216    THE  HOUSE  FLY— DISEASE  CARRIER 

on  cool  nights,  he  bases  another  line  of  attack,  which 
is  to  make  a  hole  in  the  window  screen,  with  the  guid- 
ing strips  outside  and  the  trap  inside,  thus  catching 
all  the  flies  that  attempt  to  enter  the  kitchen  in  that 
way.  He  has  tested  this  device,  but  thinks  that  it  can- 
not compete  with  the  garbage-can  trap. 

Professor  Hodge  (1910)  points  out  that  there  is 
much  yet  to  be  known  about  the  biology  of  the  adult 
typhoid  fly,  its  favorite  foods,  its  needs  for  water,  its 
habits  in  seeking  shelter,  length  of  life,  and  the  dis- 
tance it  flies,  but  he  thinks  that  wrhat  little  we  know 
indicates  that  the  strategic  point  of  attack  is  the  adult. 
He  states  that  we  have  been  long  working  on  this 
theory  unintelligently  and  ineffectively  with  sticky  or 
poisonous  fly  paper  and  traps,  but  that  these  means 
have  been  employed  only  to  kill  the  comparatively  few 
flies  that  gain  entrance  to  our  houses. 

"Carry  the  war  into  Africa;  develop  the  means  of 
attack  seriously  and  effectively  in  the  out-of-doors,  and 
I  fully  believe  that  there  will  be  no  filth  flies  to  go 
back  to  the  compost  heaps  and  barnyards  to  lay  their 
eggs."  After  using  his  traps  for  a  period,  he  found  it 
possible  to  dine  on  the  porch;  as  he  expressed  it,  he 
had  turned  the  tables  on  the  flies,  and  put  them  in  a 
prison  and  let  himself  out.  Hodge  wishes  to  stimulate 
invention  towards  making  effective  out-of-doors  fly 
traps,  and  he  urges  experiments  with  different  baits. 
He  states  that  he  did  enough  in  the  summer  of  1910 
to  be  convinced  that  any  country  home  "a  half  mile 
away  from  its  nearest  ignorant  neighbor,  or  any  town- 


PREVENTIVE  MEASURES  217 

or  city,  could  completely  exterminate  the  filth  fly  by 
intelligent  and  co-operative  effort  during  the  months 
of  April  and  May  (and  possibly  June)  of  any  year." 

In  this  connection  it  may  be  well  to  call  attention 
to  the  device  invented  by  Kellers  (1911),  which  is  a 
wire  gauze  garbage-can  holder  which  will  contain  sev- 
eral garbage  cans.  It  allows  daily  inspection  and  free 
circulation  of  air.  It  aids  in  the  suppression  of  the 
fly  nuisance  and  the  prevention  of  the  scattering  of 
putrescent  material  by  rats,  cats,  and  other  animals. 
The  designer  of  the  holder  is  a  hospital  steward  in  the 
United  States  Navy,  and  the  one  first  designed  is  in 
use  at  the  U.  S.  Naval  Hospital,  Puget  Sound.  Some 
such  arrangement  for  hospitals  and  other  similar  in- 
stitutions will  be  excellent,  and  the  addition  of  Hodge's 
fly-trap  idea  will  be  easy. 

SPECIAL  CONSIDERATIONS  FOR  TOWNS  AND  CITIES 

In  the  country,  the  individual  householder  should 
care  for  his  own  surroundings  in  such  a  way  as  to 
free  himself  from  flies,  but  in  communities  this  will  not 
be  effective.  A  single  stable  owner  by  the  proper  care 
of  his  manure  may  greatly  reduce  the  local  supply, 
but  there  will  still  be  many  thousands  from  other  stables 
in  the  neighborhood  and  from  other  possible  breeding 
places  nearby.  It  becomes  necessary  therefore  that  an 
organization  of  some  kind  or  some  system  of  co-opera- 
tion should  exist  in  communities. 


218    THE  HOUSE  FLY— DISEASE  CARRIER 

Organisation 

In  a  number  of  towns  and  cities  in  the  United  States, 
the  initiative  in  the  fly  crusade  has  been  taken  by  health 
officers,  but  in  the  majority  of  communities  the  health 
officials  have  to  be  stirred  up.  In  some  cases,  as  in  the 
State  of  Florida,  the  whole  State  crusade  has  been 
begun  by  the  State  officials  and  they  have  stirred  up  the 
town  officials.  In  a  few  communities — but  these  are 
very  few — private  practitioners  have  been  the  exciting 
cause  of  anti-fly  work.  In  one  State  only,  so  far  as 
the  writer  knows,  has  the  State  medical  association 
established  a  fly  committee  which  has  taken  it  upon 
itself  to  carry  information  concerning  the  typhoid  fly 
into  every  portion  of  the  State. 

Elsewhere,  and  here  are  the  majority  of  instances  in 
which  anti-fly  work  has  been  begun,  the  beginnings 
have  been  made  either  by  a  single  private  individual 
or  by  some  local  organization,  as  a  civic  league,  a  wom- 
en's club,  or  a  town  improvement  society.  Women's 
clubs  have  done  very  effective  work  in  this  direction, 
and  it  may  be  parenthetically  stated  that  a  great  latent 
power  exists  in  these  organizations,  a  power  which  is 
only  just  beginning  to  manifest  itself.  The  energy 
shown  for  years  by  these  organizations,  while  never 
misdirected,  has  not  until  very  recently  been  directed 
towards  the  work  which  is  the  most  productive  for  the 
good  of  all,  namely,  general  sanitary  measures  with  a 
focusing  upon  one  point  after  another.  The  Women's 
Municipal  League  of  Boston,  as  an  example,  has  re- 


PREVENTIVE  MEASURES  219 

cently  taken  up  the  fly  question  through  its  department 
of  sanitation,  of  which  Mrs.  Robert  S.  Bradley  is  the 
chairman,  and  is  doing  admirable  work. 

In  most  communities  nowadays,  one  or  the  other  of 
these  organizations  or  all  of  them  exist.  In  towns 
where  there  are  no  such  organizations,  they  should  be 
started  at  once.  In  such  cases  let  any  one  convinced 
of  the  necessity  for  an  anti-fly  crusade  talk  to  his  or 
her  friends  and,  unrebuffed  by  indifference  on  the  part 
of  others,  persevere  until  a  group  is  formed.  Then 
with  perseverance  the  growth  of  the  organization  and 
the  growth  of  public  spirit  in  many  directions  will  be 
rapid. 

The  first  effort  of  such  an  organization  should  be  to 
enlist  the  sympathy  and  co-operation  of  the  health  au- 
thorities of  the  community.  This  gained,  every  pos- 
sible effort  should  be  made  to  induce  the  controllers  of 
the  appropriations  for  the  health  officials  to  realize  the 
importance  of  this  work.  Health  officers  without  funds 
at  their  disposal  for  the  employment  of  inspectors  and 
for  the  carrying  out  of  regulations  are  hopeless,  and 
therefore  the  first  step,  after  the  health  officials  them- 
selves are  convinced  of  the  desirability  of  the  work, 
is  to  secure  the  funds.  In  some  cases  this  has  been 
done  by  private  subscription,  the  money  to  be  expended 
under  the  supervision  of  the  health  officers.  In  other 
cases  private  individuals  with  sufficient  leisure  have 
had  themselves  appointed  as  health  inspectors  without 
salary,  but  by  virtue  of  the  appointment  they  are  armed 
with  the  legal  authority  which  the  health  board  has. 


220    THE  HOUSE  FLY— DISEASE  CARRIER 

Continuous  and  successful  voluntary  work  of  this  kind, 
however,  is  not  to  be  relied  upon,  and  the  campaign 
for  funds,  and  preferably  for  regularly  appropriated 
funds,  must  be  a  strenuous  one. 

Before  all  this,  however,  a  campaign  of  publicity 
must  be  inaugurated,  and  in  such  a  campaign  the  local 
newspapers  are  of  great  assistance;  in  fact  in  many 
cities  during  the  summer  of  1910  the  local  newspapers 
themselves  inaugurated  the  campaign.  Four  excellent 
instances  of  this  which  have  come  under  the  writer's 
observation  are  the  campaigns  begun  and  carried 
through  the  summer  by  the  Minneapolis  Tribune,  the 
Kansas  City  Star,  the  Milwaukee  Sentinel,  and  the 
Washington  Evening  Star. 

Mr.  Leroy  Boughner,  city  editor  of  the  Minneapolis 
Tribune,  wrote  up  his  newspaper  anti-fly  campaign  in 
an  excellent  paper  which  was  read  before  the  Decem- 
ber, 1910,  meeting  of  the  American  Civic  Association, 
and  in  his  introductory  paragraph  he  made  the  follow- 
ing explanation: 

"An  intelligent'  newspaper  campaign  against  the 
house  fly  is  not  only  a  great  benefit  to  the  community 
in  which  the  newspaper  circulates,  but  it  is  of  direct 
value  to  the  newspaper  itself,  both  in  the  increased 
prestige  it  gets  as  a  sponsor  for  civic  betterment  and 
in  the  advertising  that  accrues  from  dealers  in 
screens,  drugs,  and  sanitary  appliances.  The  cam- 
paign conducted  by  the  Minneapolis  Tribune  in  1910 
accomplished  both  results,  and  the  story  of  how  it 
was  done  is  an  interesting  one."  Could  any  but  an 


PREVENTIVE  MEASURES 

experienced  newspaper  man  have  written  that  para- 
graph ? 

Mr.  Boughner  goes  on  to  describe  how  the  literature 
furnished  by  the  American  Civic  Association  and  by 
various  State  and  city  boards  of  health  and  other 
organizations  was  collected  and  from  these  were  culled 
hundred-word  articles,  general  in  nature,  but  prepared 
in  such  a  way  as  to  attract  the  attention  of  every  reader. 
These  were  started  in  April,  and  after  they  had  been 
running  for  a  week  or  so  letters  were  sent  to  every 
club  in  Minneapolis  suggesting  that  they  endorse  the 
campaign,  and  these  resolutions  kept  coming  in  for  a 
month  or  more,  and  were  printed,  giving  a  local  tinge 
to  the  campaign.  Then  the  local  and  State  health  of- 
ficials were  interested  and  were  quoted  wherever  it 
seemed  necessary.  Then  the  State  Entomologist  was 
approached,  and  he  was  quoted.  The  use  of  gruesome 
pictures  was  avoided  as  a  rule,  but  occasionally  the 
readers  were  startled  with  a  statement  and  a  picture 
that  helped  to  intensify  the  interest.  When  the  Tuber- 
culosis Committee  of  the  Associated  Charities  advised 
drug  store  keepers  to  cover  their  wares,  the  Tribune 
took  the  matter  up  and  drew  a  fly  moral  from  it.  Very 
often  it  happened  that  the  ammunition  furnished  by 
this  paper  was  most  valuable,  and  as  an  example  Mr. 
Boughner  states  that  seven  cases  of  typhoid  in  a  suburb 
of  Minneapolis  were  traced  to  the  typhoid  fly.  Every 
change  of  weather  was  used  as  a  pretext  for  a  new 
editorial,  and  at  the  conclusion  of  the  campaign  a  big 
story  was  written  summing  up  the  results. 


222    THE  HOUSE  FLY— DISEASE  CARRIER 

As  a  rule  the  newspaper  can  be  relied  upon  in  such 
a  meritorious  campaign  as  this,  and  city  editors  should 
if  possible  be  placed  upon  the  committees  of  the  civic 
organizations.  The  newspapers,  however,  should  be 
supplemented  by  posters,  and  by  tracts  explaining  the 
whole  situation  in  a  few  striking  sentences.  This  has 
been  done  very  extensively  in  some  cities.  It  is  im- 
portant that  the  organization  should  not  rest  with  a 
single  poster  or  with  a  single  tract,  but  the  subject 
should  be  emphasized  again  and  again,  just  as  some 
of  the  newspapers  did  last  summer.  In  this  way  the 
whole  community  becomes  at  least  educated  upon  the 
subject,  and,  with  a  very  general  knowledge  of  the 
fact  that  flies  are  dangerous  as  well  as  burdensome  and 
of  the  fact  that  they  can  be  controlled,  a  great  step  has 
been  gained.  In  other  words,  with  this  education  prac- 
tically the  whole  community  will  be  found  to  support 
the  movement. 

Let  us  take  the  case  of  a  community  in  which  such 
work  has  not  yet  been  undertaken ;  let  us  suppose  it  to 
have  been  started  in  any  one  of  the  ways  which  we  have 
mentioned ;  let  us  suppose  that  an  organization  has  been 
perfected  or  is  in  process  of  being  perfected,  and  that 
the  campaign  for  publicity  is  about  to  begin.  The 
easiest  way  to  get  ammunition  is  to  write  to  the  Secre- 
tary of  the  American  Civic  Association,  Mr.  Richard 
B.  Watrous,  whose  address  is  Union  Trust  Building, 
Washington,  D.  C.  The  fly  Committee  of  this  asso- 
ciation, of  which  Mr.  Edward  Hatch,  Jr.,  of  New 
York,  is  the  chairman,  has  done  some  very  energetic 


PREVENTIVE  MEASURES  223 

work,  and  the  whole  association  seeks  the  opportunity 
to  co-operate  directly  with  civic  societies  of  every  char- 
acter, such  as  women's  clubs,  local  civic  leagues,  con- 
sumers' leagues,  school  improvement  societies,  and  all 
organized  bodies,  in  a  direct  crusade  against  the  ty- 
phoid fly. 

The  association  publishes  bulletins  with  full  infor- 
mation as  to  the  life  history  and  habits  of  this  fly  and 
with  the  most  practical  suggestions,  secured  after  con- 
ference with  the  leading  physicians  and  entomologists. 
These  bulletins  are  sent  to  societies  in  quantities,  but 
there  is  sometimes  a  small  charge  for  very  large  quan- 
tities. The  association  also  co-operates  directly  in  pro- 
viding press  clipping  sheets  that  may  be  used  to  great 
advantage  with  local  newspapers,  calling  attention  to 
the  dangers  in  permitting  flies  to  breed  unrestrictedly. 
It  maintains  also  a  department  of  lantern  slides,  which 
includes  a  large  collection  of  pictures,  some  of  them 
descriptive  of  the  life  history  of  Musca  domestica,  and 
others  being  reproductions  of  striking  cartoons  from 
the  newspapers,  and  of  effective  posters  that  have  been 
used  by  health  boards  and  may  be  used  for  display  in 
public  places,  such  as  shops,  railroad  stations,  and  on 
the  street  cars,  to  call  attention  to  the  dangers  sur- 
rounding the  existence  of  the  fly.  It  has  also  a  very 
effective  moving-picture  film  which  can  be  rented  by 
societies  and  which  is  a  most  effective  manner  of  pre- 
senting vividly  the  objectionable  habits  of  the  house 
fly. 

The  association  has  also,  for  use  by  societies  willing 


THE  HOUSE  FLY— DISEASE  CARRIER 

to  pay  express  charges,  a  large  cabinet  containing  ex- 
hibits of  every  character,  such  as  posters,  bulletins,  and 
actual  pictures  of  flies  in  their  breeding  places  and  as 
distributers  of  disease.  This  cabinet  can  be  set  up  in 
public  places  to  great  advantage.  One  of  the  pictures 
in  this  cabinet  indicates  the  air-line  flight  of  the  typhoid 
fly  from  the  garbage  pail  to  the  breakfast  table;  an- 
other shows  a  stable  with  an  enormous  manure  pile, 
and  enlarged  figures  on  the  development  of  the  fly.  A 
third  pictures  food  exposed  on  the  streets  and  swarm- 
ing with  flies.  A  fourth  is  a  photograph  of  a  privy 
vault  swarming  with  flies,  close  to  the  kitchen  door. 
Another  is  a  reproduction  of  the  striking  fly  poster 
of  the  Florida  State  Board  of  Health  (shown  in  Fig. 
21 ).  An  admirably  worded  placard  reads,  "If  there 
is  any  contagious  disease  in  the  neighborhood,  beware 
of  flies." 

Interesting  the  Children 

Considering  the  exasperating  conservatism  of  the 
public  at  large  when  the  anti-mosquito  campaigns  be- 
gan to  be  inaugurated  ten  years  or  more  ago,  and  the 
fact  that  even  after  mosquitoes  had  been  written  about 
and  preached  about  until  it  would  seem  that  no  intelli- 
gent citizen  in  the  country  could  have  failed  to  be  con- 
vinced of  such  admirably  demonstrated  facts  as  the 
carriage  of  malaria  and  yellow  fever  by  certain  of  these 
dangerous  creatures,  and  of  the  perfect  practicability 
of  a  startling  reduction  in  their  numbers  by  the  ex- 
penditure of  a  certain  amount  of  money  and  hard  work, 
the  majority  still  remained  ignorant  or  unconvinced; 


From   FLIES   and  FILTH 
to  FOOD  and  FEVER 


The  State  Board  of  Health  • 
of  Florida 

A  SKS  YOI '  to  carefully  tad  attentively  r«a«l  rt*»*  card 
•*>  7//A.V.  put  ihv  fHMbMidMcdl  to  youncH.  »»utrK 
flics  should  not  tx.  dtMniytd.  «>f.  at  kj«t.  an  effort  be 
(nmi  (..illuiina  food  prepared  few  you  to  cat. 


F//Vj  an-  disease  carriers 

Live  and  breed  in  all  kinds  of  filth 

I  iifcct  food  and  drink  by  germ-laden  feet 

female  fly  can  lay  150  eggs 
Should  be  kept  out  of  dwellings 


STATE  BOARD  o/  HEALTH 


£*.'"«£ 


Fig.  21. — Poster  issued  by  the  Florida  State  Board  of 
Health ;  greatly  reduced. 


PREVENTIVE  MEASURES  225 

considering  this  delay,  it  is  a  delight  to  see  the  com- 
parative rapidity  with  which  the  anti-house-fly  idea  is 
spreading.  Possibly  had  this  latter  crusade  been  be- 
gun first  it  would  not  have  moved  so  rapidly ;  possibly 
the  education  which  people  have  had  in  regard  to  mos- 
quitoes makes  them  more  ready  to  accept  the  ideas  that 
are  being  put  forward  by  the  anti-fly  movers. 

But  in  the  case  of  mosquitoes,  in  more  than  one  com- 
munity it  was  found  absolutely  impossible  to  do  any- 
thing with  the  adults,  and  education  was  begun  with 
the  children  in  the  schools.  Probably  the  first  of  this 
work  was  carried  on  by  Prof.  C.  F.  Hodge  in  Worces- 
ter, Mass.,  in  1901  or  1902,  and  he  was  very  successful 
in  interesting  the  school  children  in  the  search  for  mos- 
quito breeding  places. 

The  most  serious  and  productive  effort,  however,  was 
made  at  San  Antonio,  Texas,  a  year  or  two  later,  at 
the  initiative  of  Dr.  J.  S.  Lankford.  The  school  board 
approved  the  idea  of  endeavoring  to  educate  all  of  the 
school  children  of  the  city  in  prophylaxis,  and  to  make 
sanitarians  out  of  all  of  them.  The  best  medical  lit- 
erature on  the  subject  was  procured  and  furnished  to 
the  teachers.  A  circular  letter  was  sent  to  them  out- 
lining the  proposed  course,  and  offering  a  cash  prize 
for  the  best  model  lesson  on  the  subject.  Teachers 
became  greatly  interested;  a  crude  aquarium  with 
eggs  and  wrigglers  was  kept  in  every  schoolroom  where 
the  pupils  could  watch  them  develop,  and  large  mag- 
nifying glasses  were  furnished  in  order  that  they  might 
study  to  better  advantage.  The  children  were  en- 


226    THE  HOUSE  FLY— DISEASE  CARRIER 

couraged  to  make  drawings  on  the  blackboard  of  mos- 
quitoes in  all  stages  of  development.  Lessons  were 
given ;  compositions  were  written  on  the  subject ;  com- 
petitive examinations  were  held,  and  groups  of  boys 
and  girls  were  sent  out  with  the  teachers  on  searching 
expeditions  for  the  breeding  places. 

Rivalry  sprang  up  between  the  10,000  public  school 
children  in  the  city  in  finding  and  reporting  to  the 
health  office  the  greatest  number  of  breeding  places 
found  and  destroyed.  Records  were  kept  on  the  black- 
boards in  the  schools  of  the  progress  of  the  competi- 
tion, and  great  enthusiasm  was  stirred  up.  In  addition 
to  these  measures  a  course  of  stereopticon  lectures  was 
arranged,  grouping  the  pupils  in  audiences  of  about 
1,000,  from  the  high  school  down,  and  in  Doctor  Lank- 
ford's  wrords,  "It  was  an  inspiring  sight  to  watch  these 
audiences  of  1,000  children,  thoughtful,  still  as  death, 
and  staring  with  wide-open  eyes  at  the  wonders  re- 
vealed by  the  microscope.  It  seemed  to  me  that  in 
bringing  this  great  question  of  preventive  medicine  be- 
fore public  school  children  we  had  hit  upon  a  power 
for  good  that  could  scarcely  be  over-estimated."  As 
a  result  there  was  a  decided  diminution  in  the  numbers 
of  mosquitoes  in  San  Antonio.  There  was  some  oppo- 
sition among  the  people,  but  the  movement  on  the 
whole  was  very  popular,  and  the  mortality  of  the  city 
from  malarial  trouble  was  reduced  seventy-five  per  cent, 
the  first  year  after  the  work  was  begun,  and  in  the 
second  year  it  was  entirely  eliminated  from  San  An- 
tonio! 


PREVENTIVE  MEASURES  227 

It  follows  that  in  "organizing  community  work,  not 
only  against  mosquitoes  but  against  flies  as  well,  the 
school  children  must  be  counted  upon  as  a  most  im- 
portant factor.  Almost  all  children  are  born  naturalists, 
and  interest  in  such  things  comes  to  them  more  readily 
than  anything  else  outside  of  the  necessities  of  life. 
They  are  quick-witted,  wonderfully  quick-sighted,  and 
as  finders  out  of  breeding  places  they  cannot  be  ap- 
proached except  by  adults  with  the  most  especial  train- 
ing. 

The  specific  question  of  interesting  school  children 
in  the  house-fly  campaign  was  brought  up  at  the  De- 
cember meeting  of  the  American  Civic  Association. 
It  was  introduced  by  the  writer  and  had  also  been 
previously  considered  by  the  Fly  Committee  of  the  as- 
sociation, of  which,  as  previously  stated,  Mr.  Hatch 
is  the  chairman.  The  association  plans  to  offer  prizes 
for  school  children  in  certain  selected  cities,  prizes  ag- 
gregating for  the  ordinary  town  say  from  thirty  to 
fifty  dollars.  These  are  to  be  competed  for  by  chil- 
dren of  the  public  schools,  and  in  two  classes:  first, 
young  children  between  the  ages  of  nine  and  eleven; 
and,  second,  children  from  twelve  to  fifteen;  so  that 
the  younger  children  will  not  come  into  competi- 
tion with  the  older  and  presumably  better  prepared 
ones. 

It  will  be  necessary  in  order  to  do  this,  in  some  cases, 
to  do  a  little  work  with  school  boards,  so  that  they 
may  be  willing  to  admit  into  the  schools  the  literature 
which  will  be  the  basis  of  the  essays.  Health  boards 


228    THE  HOUSE  FLY— DISEASE  CARRIER 

and  medical  societies,  however,  will  naturally  be  will- 
ing to  co-operate.  The  association  hopes  that  there 
will  be  public-spirited  citizens  in  the  various  towns 
who  will  themselves  institute  competitions  of  this 
sort. 

Referring  to  this  matter,  in  a  paper  read  later  at 
the  meeting.  Doctor  Woods  Hutchinson  said,  "I  be- 
lieve that  we  could  utilize  an  enormous  amount  of 
good  enthusiasm  and  good  human  activity  going  to 
waste  under  the  name  of  'mischief/  and  if  we  could 
take  the  enthusiasm  of  a  boy  and  his  delight  of  get- 
ting into  mischief  and  put  him  to  work  on  the  fly 
problem,  I  believe  we  could  do  a  great  deal  towards 
putting  any  community  into  a  practical  process  of 
cleansing." 

An  important  point  which  we  have  not  yet  men- 
tioned is  that  it  will  be  important  to  have  one  or  more 
well-posted  physicians  on  the  advisory  board  of  any 
fly-fighting  organization,  in  order  that  the  tendency 
of  enthusiastic  people  to  make  extreme  statements 
which  are  unscientific  and  not  perfectly  justified  by 
facts  may  be  held  within  bounds  by  others  posted  as 
to  scientific  methods  and  as  to  the  exact  truth  of  the 
sanitary  aspects  of  the  crusade.  The  advisory  com- 
mittee, and  especially  its  medical  members,  will  find 
themselves  much  embarrassed  by  the  difficulty  of  re- 
fraining from  over-statements. 

The  fly  situation  is  an  extremely  bad  one  in  all  truth, 
but  if  it  is  exaggerated  in  order  to  attract  and  inten- 
sify universal  popular  interest,  the  very  exaggeration 


PREVENTIVE  MEASURES  229 

will  have  the  contrary  effect  upon  the  minds  of  con- 
servative people,  and  upon  medical  men  who  stand 
for  absolute  exactness  of  statement.  Moreover,  there 
are  in  every  large  community  scientific  men  trained  in 
laboratory  methods,  who  believe  that  exact  truth  can 
be  obtained  only  by  laboratory  methods  and  who  hold 
the  verdict  of  "not  proven"  against  certain  things  which 
on  the  strongest  circumstantial  evidence  have  been 
claimed  against  the  fly.  It  is  best  to  carry  this  con- 
servative class  with  you  if  you  can,  and  this  can  be 
done  by  a  certain  moderation  in  statement  and  by  the 
avoidance  of  methods  which  may  be  termed  ultra-yel- 
low-journalistic. 

And  there  is  the  quandary:  how  to  frighten  the  ig- 
norant and  slothful  and  educate  them  on  the  fly  ques- 
tion without  creating  a  distaste  for  your  methods  and 
a  consequent  lack  of  helpful  interest  on  the  part  of 
some  who  could  be  of  the  most  valuable  assistance.  The 
writer,  although  he  was  trained  to  scientific  methods 
and  has  followed  them  for  many  years,  is  inclined  to 
think  that  over-statement  to  bring  about  a  great  san- 
itary reform  may  be  justified  so  long  as  this  over- 
statement is  based  upon  sound  circumstantial  evidence. 

He  is  thoroughly  optimistic  as  to  the  progress,  in 
the  immediate  future,  of  the  campaign  of  education 
against  the  typhoid  fly,  and  he  is  certain  in  his  own 
mind  that,  take  the  country  by  and  large,  and  includ- 
ing all  classes  of  citizens,  whether  living  in  cities,  towns, 
villages,  or  on  farms,  there  is  no  single  way  in  which 
the  mortality  rate  of  the  country  can  be  so  rapidly  de- 


230    THE  HOUSE  FLY— DISEASE  CARRIER 

creased,  and,  per  contra,  the  health  of  the  people  so 
easily  bettered,  as  by  the  reduction  of  the  numbers  of 
the  house  fly  to  a  negligible  quantity. 

BOARDS  OF  HEALTH 

The  health  officers,  both  State  and  local,  of  the  coun- 
try have  their  associations  and  organizations  of  one 
kind  or  another.  Probably  all  of  them  are  members 
of  the  Public  Health  Association  of  the  United  States. 
All  are  thus,  or  should  be,  acquainted  with  the  work 
of  all  the  rest,  since  there  is  a  constant  interchange  of 
ideas  at  the  meetings  and  a  constant  interchange  of 
publications  in  the  intervals  between  the  meetings.  But 
it  is  well  for  citizens'  associations,  civic  leagues,  wom- 
en's clubs  who  take  up  sanitary  matters,  and  public- 
spirited  citizens  generally,  to  know  what  an  effective 
health  officer  or  board  of  health  should  do,  in  order 
that  they  may  intelligently  criticise  the  administration 
of  such  matters  by  their  own  local  officials  in  case, 
when,  as  it  sometimes  happens,  these  are  lax;  or,  on 
the  other  hand,  back  up  efficient  officials  where  village 
trustees  or  town  councils  or  city  boards  of  aldermen 
are  not  disposed  to  grant  the  funds  necessary  to  carry 
out  proper  sanitary  regulations. 

This  is  our  excuse  for  quoting  at  length  the  sanitary 
regulations  of  the  District  of  Columbia  in  so  far  as 
they  relate  to  the  fly  problem.  The  regulations  are 
sound  and  the  citizens  of  the  District  have  no  cause 
in  this  respect  to  criticise  the  health  officer,  but  the 
appropriating  body  in  this  case  (and  it  happens  to  be 


PREVENTIVE  MEASURES  231 

the  Congress  of  the  United  States)  has  not  down  to 
the  present  time  appropriated  sufficient  funds  to  carry 
these  regulations  into  full  effect.  Good  regulations 
require  an  efficient  force  of  inspectors,  and  efficient  in- 
spectors must  be  paid.  Dr.  William  C.  Woodward, 
the  health  officer  of  the  District,  has  called  the  writer's 
attention  to  the  fact  that  it  really  requires,  from  the 
practical  standpoint,  two  inspectors  to  do  one  inspec- 
tor's work,  since  a  solitary  inspector,  coming  into  court 
with  a  charge  of  violation  of  the  regulations  against 
a  given  citizen,  is  invariably  confronted  with  such  a 
mass  of  testimony  against  his  charge  that  he  is  sworn 
out  of  court.  He  must  take  some  one  along  with  him 
to  prove  it.  The  orders  in  question  may  be  briefly  con- 
densed as  follows;  their  full  text  will  be  found  in  Ap- 
pendix III : 

All  stalls  in  which  animals  are  kept  shall  have  the 
surface  of  the  ground  covered  with  a  water-tight  floor. 
Every  person  occupying  a  building  where  domestic 
animals  are  kept  shall  maintain,  in  connection  there- 
with, a  bin  or  pit  for  the  reception  of  manure,  and 
pending  the  removal  from  the  premises  of  the  manure 
from  the  animal  or  animals  shall  place  such  manure  in 
said  bin  or  pit.  This  bin  shall  be  so  constructed  as  to 
exclude  rain  water,  and  shall  in  all  other  respects  be 
water-tight,  except  as  it  may  be  connected  with  the 
public  sewer.  It  shall  be  provided  with  a  suitable  cover 
and  constructed  so  as  to  prevent  the  ingress  and  egress 
of  flies.  No  person  owning  a  stable  shall  keep  any 
manure  or  permit  any  manure  to  be  kept  in  or  upon 


232    THE  HOUSE  FLY— DISEASE  CARRIER 

any  portion  of  the  premises  other  than  the  bin  or  pit 
described,  nor  shall  he  allow  any  such  bin  or  pit  to  be 
overfilled  or  needlessly  uncovered.  Horse  manure  may 
be  kept  tightly  rammed  into  well-covered  barrels  for 
the  purpose  of  removal  in  such  barrels.  Every  person 
keeping  manure  in  any  of  the  more  densely  populated 
parts  of  the  District  shall  cause  all  such  manure  to  be 
removed  from  the  premises  at  least  twice  every  week 
between  June  ist  and  October  3ist,  and  at  least  once 
every  week  between  November  ist  and  May  3ist  of  the 
following  year.  No  person  shall  remove  or  transport 
any  manure  over  any  public  highway  in  any  of  the 
more  densely  populated  parts  of  the  District  except  in 
a  tight  vehicle,  which,  if  not  inclosed,  must  be  effectu- 
ally covered  with  canvas,  so  as  to  prevent  the  manure 
from  being  dropped.  No  person  shall  deposit  manure 
removed  from  the  bins  or  pits  within  any  of  the  more 
densely  populated  parts  of  the  District  without  a  per- 
mit from  the  health  officer.  Any  person  violating  any 
of  these  provisions  shall,  upon  conviction  thereof,  be 
punished  by  a  fine  of  not  more  than  forty  dollars  for 
each  offense. 

In  addition  to  this  excellent  ordinance,  others  have 
been  issued  from  the  health  department  of  the  District 
of  Columbia  which  provide  against  the  contamination 
of  exposed  food  by  flies  and  by  dust.  The  ordinances 
are  excellently  worded  so  as  to  cover  all  possible  cases. 
They  provide  for  the  registration  of  all  stores,  markets, 
cafes,  lunch  rooms,  or  of  any  other  place  where  food 
or  beverage  is  manufactured  or  prepared  for  sale, 


PREVENTIVE  MEASURES  233 

stored  for  sale,  offered  for  sale,  or  sold,  in  order  to 
facilitate  inspection,  and  still  more  recent  ordinances 
provide  for  the  registration  of  stables.  An  excellent 
campaign  was  begun  during  the  summer  of  1908 
against  insanitary  lunch  rooms  and  restaurants.  A 
number  of  cases  were  prosecuted,  but  conviction  was 
found  to  be  difficult  for  the  reasons  already  mentioned. 
All  boards  of  health  should  follow,  and  doubtless 
are  following,  the  very  interesting  experiment  which 
the  Louisiana  Board  is  now  making,  of  sending  out 
a  "Health  Train"  and  visiting  one  town  after  another, 
conducting  health  demonstrations  and  lectures  and 
showing  moving  pictures  which  appeal  directly  to  the 
intelligence  of  every  one.  Three  hundred  and  fifty 
towns  in  Louisiana  have  already  been  visited  in  this 
way,  and  education  on  the  house  fly  has  been  a  very 
important  part  of  the  work.  The  first  train  was  sent 
out  from  New  Orleans  November  5,  1910,  and  con- 
sisted of  two  especially  equipped  cars.  An  illustrated 
article  on  the  subject  was  published  in  the  Quarterly 
Bulletin  of  the  Louisiana  State  Board  of  Health,  i, 
No.  4,  November  15,  1910. 

ARMY  CAMPS 

The  severe  lessons  of  the  past  in  regard  to  fly-borne 
typhoid  in  army  camps  have  borne  fruit,  and  there  is 
reason  to  believe  that  among  the  more  civilized  nations 
in  the  future  there  will  be  no  recurrence  of  the  frightful 
experiences  of  the  summer  of  1898  and  of  those  in 
South  Africa.  It  is  with  the  greatest  pleasure  that  the 


THE  HOUSE  FLY— DISEASE  CARRIER 

writer  learns,  just  as  this  book  is  going  to  the  press, 
of  the  regulations  in  force  at  San  Antonio,  Texas,  in 
the  large  encampment  of  troops  there  present.  The 
camp  sanitary  regulations  appear  to  be  of  the  most 
perfect  kind  and  to  be  admirably  enforced.  An  account 
of  the  methods  used  will  doubtless  soon  be  published 
by  the  Medical  Corps  of  the  Army,  and  the  writer  re- 
frains from  anticipating  such  publication,  since  the  ob- 
servations on  which  he  bases  this  statement  of  the  per- 
fection of  the  arrangements  have  been  made  by  persons 
not  connected  with  the  service.  He  may  state  however 
that  the  Medical  Corps  deserves  the  greatest  praise  for 
the  introduction  of  novel  and  very  perfect  arrangements 
for  the  disposal  of  all  camp  waste. 


OTHER  FLIES  FREQUENTING  HOUSES 

IN  a  series  of  experiments  carried  on  during  the  sum- 
mer of  1900,  flies  were  collected  in  the  kitchens  and 
dining-rooms  of  many  houses  in  many  different  parts 
of  the  country.  These  collections  were  made  in  the 
States  of  Massachusetts,  New  York,  Pennsylvania, 
District  of  Columbia,  Virginia,  Florida,  Georgia,  Lou- 
isiana, Nebraska,  and  California.  In  all,  23,087  flies 
were  thus  collected.  On  critical  examination  in  Wash- 
ington by  Mr.  Coquillett,  22,808,  that  is  to  say,  ninety- 
eight  and  eight-tenths  per  cent,  of  the  whole  number 
captured,  were  Musca  domestica.  The  remainder,  con- 
sisting of  one  and  two-tenths  per  cent,  of  the  whole, 
comprised  various  species,  none  of  them  of  any  espe- 
cial significance.  These  and  a  few  others  will  be  con- 
sidered in  more  or  less  detail  in  the  following  para- 
graphs. 

Of  course  there  are  other  flies  than  these  occasionally 
found  in  houses,  and  some  quite  commonly  so.  Mos- 
quitoes are  flies,  that  is  to  say,  they  belong  to  the  or- 
der Diptera,  but  they  form  no  part  of  the  present  book : 
they  are  treated  in  other  volumes.  Aside  from  those 
especially  mentioned  here,  other  flies  of  the  same  group 
are  occasionally  found,  not  attracted  to  a  house,  but 
trying  to  escape  from  it.  Occasionally,  however,  some 

235 


236    THE  HOUSE  FLY— DISEASE  CARRIER 

of  the  biting  flies  known  as  gad  flies  or  horse  flies,  of 
the  family  Tabanidse,  enter  houses  seeking  blood.  They 
bite  painfully,  but  for  the  most  part  prefer  to  stay  out 
of  doors,  although  they  frequent  shady  situations  as  a 
rule.  They  are  common  in  pine  woods,  and  the  in- 
habitants of  summer  houses  built  in  such  locations  are 
occasionally  bothered  by  them  to  some  extent.  Trav- 
elers in  Alaska,  where  some  of  these  gad  flies  abound 
during  the  short  and  damp  summer,  have  stated  that 
they  sometimes  become  almost  a  scourge  in  the 
cabins. 

The  species  which  we  are  about  to  mention  more 
fully,  however,  are  the  commonest  of  the  flies  found 
in  houses,  although  their  numbers  are  so  insignificant 
as  to  be  almost  disregarded  when  compared  with  Alnsca 
dorncstica. 

THE  CLUSTER  FLY  (Pollcnia  rudis  Fabr.) 

There  is  a  rather  sluggish  fly,  a  little  larger  than  the 
house  fly,  which  is  frequently  found  in  houses,  espe- 
cially in  the  spring  and  fall.  It  has  a  dark-colored, 
smooth  abdomen  and  a  sprinkling  of  yellowish  hair. 
It  is  very  sluggish,  in  the  fall  especially,  and  at  such 
times  it  may  be  picked  up  readily.  It  is  subject  to  the 
attacks  of  a  fungous  disease  which  causes  it  to  die 
upon  window  panes,  where  it  is  often  seen  surrounded 
with  a  white  efflorescence.  (Fig.  22.) 

The  cluster  fly  is  a  European  species,  and  the  date 
of  its  introduction  into  the  United  States  is  not  known. 
It  could  easily  have  been  brought  over  upon  slow  sail- 


THE  CLUSTER  FLY  237 

ing  vessels,  especially  in  the  cooler  season  of  the  year, 
since  it  apparently  hibernates  in  the  adult  condition  and 
seeks  the  shelter  of  cracks  and  crevices.  It  is  men- 
tioned by  Loew  in  1864  as  one  of  the  flies  common  to 
Europe  and  America.  Attention  was  first  particularly 
called  to  it  and  to  its  house  habits  by  Dr.  W.  H.  Ball, 
of  the  Smithsonian  Institution.  In  an  article  published 
in  the  Proceedings  of  the  U.  S.  National  Museum  for 
1882  (Vol.  V,  pp.  635-636)  Doctor  Dall  related  that 
far  several  years  he  had  heard  of  a  fly  which  was  a 
great  nuisance  in  country  houses  near  Geneva,  N.  Y. 
He  secured  specimens  of  the  fly,  which  were  turned 
over  to  professor  Riley  for  identification. 

One  of  his  relatives  in  Geneva  wrote  him  that  it  was 
probably  thirty  years  since  the  fly  had  first  appeared 
in  that  neighborhood.  They  were  at  once  a  terror  to 
good  housekeepers  and  a  constant  surprise,  since  they 
were  found  in  beds,  in  pillow  slips,  under  table  covers, 
behind  pictures,  in  wardrobes,  and  in  all  sorts  of  places. 
In  clean,  dark  bedchambers  seldom  used,  they  would 
form  in  large  clusters  about  the  ceilings.  They  seemed 
oily,  and  if  crushed  left  a  great  grease  spot  on  the  floor. 
The  correspondent  stated  that  about  the  first  of  April 
they  came  out  of  the  grass  and  flew  up  to  the  sunny 
side  of  houses,  which  they  entered.  They  remained  in 
evidence  until  some  time  in  May,  and  then  disappeared 
and  were  not  seen  again  until  September,  when  they 
came  and  remained  all  winter.  They  were  stated  to  be 
very  sluggish — to  crawl  rather  than  to  fly  away  when 
disturbed.  They  were  said  to  be  often  found  in  incred- 


238    THE  HOUSE  FLY— DISEASE  CARRIER 

ible  numbers  under  buildings,  between  the  earth  and 
the  floor. 

Dr.  J.  A.  Lintner,  in  his  Ninth  Report  of  the  State 
Entomologist  of  New  York  (Albany,  1893),  gave  a 
number  of  instances  of  like  occurrences  of  this  fly  in 
houses,  both  in  spring  and  in  winter,  in  various  parts  of 
New  York  State.  A  good  description  was  given  by  a 
correspondent  of  the  Washington  Bureau  of  Entomol- 
ogy, living  in  Lasalle  County,  Illinois.  The  corre- 
spondent stated  that  the  cluster  fly  had  been  a  pest,  in 
her  household  for  fifteen  years.  She  wrote,  "They 
seem  to  prefer  to  occupy  the  rooms  on  the  north  side 
of  the  house  and  those  that  are  used  but  little.  They 
gather  in  large  bunches  in  the  corners  and  along  the 
edge  of  the  ceiling  of  the  room.  They  cannot  be  driven 
out  as  other  flies,  but  must  be  killed  outright  to  get 
rid  of  them,  and  when  you  mash  them  the  odor  is  like 
that  of  honey.  We  have  tried  nearly  everything  that 
we  heard  of  that  was  recommended  to  us,  with  no  ef- 
fect. It  seems  impossible  to  get  rid  of  them  or  to  keep 
them  out  of  the  house,  for  they  crawl  in  through  the 
smallest  places  in  the  windows." 

Other  correspondents  have  reported  the  odor  of  the 
crushed  bodies  as  being  very  disagreeable. 

Incredible  as  it  must  seem,  practically  nothing  is 
known  about  the  early  stages  of  this  abundant  and  trou- 
blesome fly.  European  writers  either  admit  that  they 
know  nothing  about  it  or  give  rather  vague  statements. 
Robineau  Desvoidy,  speaking  of  the  genus  Pollenia  as 
a  whole,  states  that  their  eggs  are  laid  in  decomposing 


Fig.  22.— The  cluster  fly  (Pollcnia  rudis)  ;  greatly  enlarged.    (Original.) 


Fig.  23.— The  biting  house  fly  (Stomoxys  calcitrant)  ;  larva  and  pupa  at 

right;  head  at  left  and  anal  spiracle  of  larva  below;  greatly 

enlarged.     (Author's  illustration.) 


THE  CLUSTER  FLY  239 

animal  and  vegetable  matter.  Macquart,  also  speaking 
of  the  genus  and  not  especially  of  this  species,  states 
that  the  larvae  develop  in  the  manure  pile  and  cow 
droppings.  The  only  definite  recorded  observation 
which  seems  to  have  been  made  upon  the  actual  breed- 
ing habits  of  this  species,  in  fact,  is  the  rearing  of  a 
single  specimen  from  cow  dung.  This  single  specimen 
was  reared  in  the  Insectary  of  the  Bureau  of  Entomol- 
ogy December  23,  1899.  The  writer  has,  however, 
received  a  letter  from  Prof.  J.  S.  Hine,  of  the  Ohio 
State  University,  in  which  he  states  that  during  the 
summer  of  1910  he  reared  numbers  of  cluster  flies,  to- 
gether with  other  dipterous  insects  from  accidental  cow 
droppings  in  the  pasture.* 

In  the  absence  of  further  exact  observations,  it  is 
fair  to  suppose  that  the  cluster  fly  breeds  in  decompos- 
ing animal  matter  of  some  kind  or  other,  and  it  is  alto- 
gether likely  that  measures  taken  against  the  breeding 
places  of  the  true  Musca  domestica  will  also  be  meas- 
urably effective  against  this  species.  There  is  as  yet, 
however,  the  possibility  that  it  may  breed  in  rich  soil 
or  decomposing  vegetable  substances.  It  is  difficult  to 
keep  out  of  the  house  by  screening,  but  it  may  be  killed 
by  a  light  kerosene  spray  or  by  the  free  use  of  a  fresh 
pyrethrum  powder. 

Marlatt  (Insect  Life,  Vol.  IV,  1891)  records  an  ex- 
traordinary mortality  among  these  flies  which  he  no- 
ticed on  the  grounds  of  the  Department  of  Agriculture 
in  the  autumn  of  that  year.  He  found  often  as  many 
as  eight  or  ten  flies  fastened  by  a  fungous  growth  to 

*D.  Keilin  (C.  R.  Soc.  de  Biologic,  Vol.  67,  p.  201)  states  that 
the  larvae  of  Pollenia  are  parasitic  in  certain  earth-worms. 


240    THE  HOUSE  FLY— DISEASE  CARRIER 

the  under  side  of  leaves  near  the  buildings.  Specimens 
of  these  fungus-infested  flies  were  sent  to  Doctor  Thax- 
ter  of  Harvard  University,  and  the  organism  that  killed 
them  was  found  to  be,  not  Empusa  musca,  as  was 
thought,  but  Empusa  amcricana. 

THE  BITING  HOUSE  FLY  (Stomoxys  calcitrant  L.) 

This  insect  is  rather  closely  related  to  the  house  fly 
and  greatly  resembles  it  in  appearance,  in  fact  it  is  dif- 
ficult to  distinguish  one  from  the  other  except  by  the 
closest  observation.  Raillet  has  stated  that  the  Sto- 
moxys holds  its  head  up  while  the  house  fly  holds  its 
head  down,  but  there  are  other  ways  of  telling  them 
apart,  as  can  be  seen  by  comparing  the  illustrations  of 
the  two  species.  The  Stomoxys  is  of  the  same  gray 
color  with  dark  lines,  but  its  mouth  parts  are  quite  dif- 
ferent; in  fact  a  good  way  to  distinguish  between  the 
two  flies  is  to  allow  them  to  walk  over  your  hand ;  if 
it  bites,  Stomoxys;  if  it  does  not  it  is  probably  the 
house  fly.  It  is  this  other  species  about  which  we  are 
writing  that  gave  rise  to  the  old  saying  that  flies  begin 
to  bite  before  a  rain,  since  the  biting  house  fly  is  not 
normally  a  house  fly  at  all,  but  loves  the  out-of-doors. 

It  has  not  yet  and  probably  never  will  become  as 
truly  a  domestic  species  as  Musca  domestica.  It  is  not 
attracted  to  the  garbage  pail  and  the  kitchen  and  din- 
ing-room for  food,  but  finds  plenty  of  food  on  cattle 
and  horses  and  other  domestic  and  also  wild  animals. 
Under  certain  circumstances,  however,  it  may  become 
a  very  common  resident  of  houses.  (Fig.  23.) 


THE  BITING  HOUSE  FLY 

Dr.  John  B.  Smith,  at  a  meeting  of  the  Entomolog- 
ical Society  of  Washington,  once  stated  that  these 
flies  were  very  abundant  at  his  house;  that  he  had 
not  been  able  to  observe  any  increase  in  numbers  in 
rainy  weather,  but  on  the  contrary  he  had  found 
them  gradually  becoming  more  abundant  until  at 
that  time  (November  ist)  they  had  almost  replaced 
the  common  house  fly,  which  was  being  rapidly  killed 
off  by  the  fungous  disease  mentioned  in  a  previous 
chapter. 

Hewitt  states  that  in  England  it  is  often  found  in 
houses,  and  he  himself  has  found  it  in  large  numbers 
in  the  windows  of  a  country  house  in  March  and  April. 
He  states  that  it  is  popularly  known  in  England  as  the 
"storm  fly"  from  its  habit  of  seeking  the  shelter  of 
houses  during  wet  weather. 

Newstead  states  that  in  England  (and  the  same  con- 
ditions hold  for  this  country)  farm  yards  and  stables 
are  the  favorite  haunts  of  this  fly,  but  that  it  occurs 
also  in  the  fields  and  parks  and  open  woods,  especially 
where  cattle  are  grazing.  He  has  seen  it  resting  on 
the  shop  fronts  of  the  main  streets  of  both  Liverpool 
and  Chester,  and  states  that  it  is  fond  of  resting  on 
surfaces  fully  exposed  to  the  sun  and  that  painted  sur- 
faces are  also  attractive  to  it.  The  greatest  number 
he  ever  saw  congregated  together  was  on  the  sunny 
side  of  a  red-painted  iron  tank  at  the  old  Chateau  de 
Goumont,  Waterloo,  Belgium.  At  night,  he  states, 
they  retire  to  some  sheltered  spot,  and  numbers  may 
be  found  at  rest  on  the  beams  and  rafters  in  open  sheds 


THE  HOUSE  FLY— DISEASE  CARRIER 

at  farm  yards,  where  they  remain  until  the  morning  sun 
tempts  them  out. 

Both  males  and  females  suck  blood.  According  to 
Osborn,  while  this  fly  inflicts  a  deep  bite  it  does  not 
gorge  itself  at  a  single  animal,  but  may  fly  from  one 
to  another  in  securing  a  meal.  From  this  fact  he  thinks 
the  idea  that  this  fly  is  apt  to  be  a  transmitter  of  glan- 
ders from  diseased  to  healthy  horses,  and  anthrax 
among  cattle,  receives  important  support.  The  punc- 
ture under  ordinary  circumstances  does  not  seem  to  be 
poisonous  to  men,  and  aside  from  the  pain  given  it  is 
less  dangerous  than  a  mosquito  bite.  Newstead  no- 
ticed a  female  drive  its  proboscis  into  the  thorax  of  a 
dead  companion  and  apparently  suck  up  the  juices  of 
its  body.  The  same  writer  permitted  one  to  suck  blood 
from  his  hand  and  observed  it  carefully  during  the 
process.  The  insect  sat  high  on  its  legs,  the  whole  of 
the  proboscis  was  straightened  and  held  vertically,  and 
the  lower  third  was  driven  into  the  flesh.  During  the 
process,  which  lasted  fifteen  minutes,  the  proboscis  was 
constantly  but  somewhat  slowly  moved  up  and  down, 
and  also  with  an  occasional  semi-rotary  movement,  like 
the  action  of  a  quarryman's  hand  drill.  There  was  no 
subsequent  irritation  or  soreness  of  any  kind.  The 
fly  died  twelve  hours  after  feeding.  During  other  ob- 
servations Newstead  found  that  the  flies  lived  for  sev- 
eral days  in  captivity,  and  that  the  females  died  either 
immediately  or  shortly  after  laying  their  eggs. 

The  biting  house  fly  has  almost  as  wide  a  geographic 
distribution  as  the  true  house  fly.  It  was  probably  orig- 


THE  BITING  HOUSE  FLY  243 

inally  an  European  species  and  has  spread  by  the  help 
of  commerce  to  many  parts  of  the  world.  It  occurs 
all  over  North  America  and  is  also  to  be  found  in  Cen- 
tral and  South  America.  It  is  also  found  in  Australia, 
China,  India,  and  the  Canary  Islands. 

The  writer  has  reared  the  biting  house  fly  from  cow 
manure  and  from  horse  manure.  I  judge  from  the 
fact  that  it  is  attracted  to  human  excreta  that  it  may 
become  a  carrier  of  intestinal  disease.  It  has  been 
reared  from  sheep's  dung  and  from  warm  decaying 
vegetable  refuse,  especially  from  piles  of  fermenting 
lawn  grass. 

Lucien  Iches,  in  the  Bulletin  de  la  Societe  Nationale 
d'Acclimatation  de  France,  March,  1909,  published  a 
very  interesting  article  on  Stomoxys  calcitrans  and  Ar- 
gentine cattle,  giving  the  results  of  a  brief  investigation 
made  by  him  in  1908  in  the  province  of  Santa  Fe,  Ar- 
gentina. The  biting  flies  swarmed  on  a  large  estate  in 
almost  incredible  numbers.  The  cattle  were  driven 
nearly  crazy  by  them.  Certain  valuable  Durham  bulls 
which  were  observed  were  covered  with  the  flies.  They 
had  lost  their  hair  in  large  spots  and  the  skin  was 
cracking. 

Monsieur  Iches  naturally  sought  at  once  for  the  prin- 
cipal breeding  places  of  the  flies,  and  found  them  to  be 
in  the  stacks  of  debris  from  the  threshing  of  wheat  and 
flax.  Larvae  and  puparia  were  found  by  the  millions 
in  the  lower  portions  of  these  piles  of  straw,  where 
some  fermentation  had  already  begun.  The  sensible 
measure  which  he  recommended  was  to  have  this  de- 


THE  HOUSE  FLY— DISEASE  CARRIER 

bris  burned  within  forty-eight  hours  after  the  com- 
pletion of  the  threshing,  the  ashes  being  used  for  fer- 
tilizing purposes.  It  turned  out  that  there  was  an  old 
provincial  law  in  the  province  of  Santa  Fe  ordering 
the  burning  of  the  debris  after  threshing,  but  it  had 
not  been  carried  out  during  recent  years,  and  therefore 
the  Stomoxys  multiplied  until  this  veritable  plague  en- 
sued. In  1888  this  Stomoxys  made  its  appearance  in 
extraordinary  numbers  near  Salem,  Oregon,  and  it  is 
altogether  likely  that  there  was  some  similar  reason 
for  its  extraordinary  abundance  that  year.  At  that 
time,  however,  its  true  breeding  places  were  not  known 
and  the  cause  of  the  outbreak  was  not  found. 

There  are  undoubtedly  many  substances  in  which 
the  biting  house  fly  breeds,  and  it  evidently  requires 
about  the  same  conditions  as  does  the  true  house  fly. 

The  larvae  and  puparia  of  this  species  have  been 
figured  by  the  writer,  but  the  full  life  history  has  been 
carefully  studied  by  Newstead.  He  found  that  the  eggs 
are  laid  in  an  irregular  heap  and  that  the  average  num- 
ber deposited  is  about  sixty.  The  egg  is  much  like  that 
of  the  house  fly,  and  is  one  millirrieter  long.  It  hatches 
in  from  two  to  three  days  in  an  average  temperature 
of  72°  F.  in  the  day  and  65°  F.  in  the  night.  The 
larva  need  not  be  described,  since  it  is  similar  to  that 
of  the  house  fly.  Newstead  found  that  in  this  stage 
they  lived  from  fourteen  to  twenty-one  days,  but  that 
the  absence  of  excessive  moisture  and  the  admission  of 
a  little  light  materially  retarded  development,  which 
then  extended  over  a  period  of  thirty-one  to  seventy- 


THE  BITING  HOUSE  FLY  245 

eight  days.  In  the  puparium  the  insect  remained  from 
nine  to  thirteen  days.  The  development  of  the  species 
is  therefore  slower  than  that  of  the  true  house  fly.  It 
is  Newstead's  opinion  that  the  winter  is  passed  chiefly 
in  the  pupal  condition.  Packard  (1874)  describes  the 
pupa  of  this  species. 

The  extraordinary  effects  of  numbers  of  the  bites  of 
this  fly,  indicated  in  the  account  of  the  epidemic  of 
1908  in  Argentina,  cannot  be  exaggerated.  Cattle  and 
horses  suffer  severely  from  these  bites  when  the  in- 
sects are  numerous.  Mr.  T.  J.  Bold,  in  the  Entomolo- 
gists' Monthly  Magazine  for  1865,  p.  143,  gives  an 
account  of  the  condition  of  these  animals  at  Long 
Benton  in  September  of  that  year.  Fourteen  cows 
were  under  treatment  by  a  veterinary  surgeon  at  one 
time.  The  animals  were  generally  bitten  on  the  out- 
side of  the  legs,  on  the  shoulders,  and,  rarely,  on  the 
neck.  In  severe  cases  the  joints  were  so  much  swollen 
that  the  animals  could  not  bend  their  legs  to  lie  down, 
and  the  swelling  from  the  inflammation  was  so  great 
that  the  outer  skin  cracked  and  the  hair  fell  off.  It 
is  stated  that  the  flies  appeared  to  prefer  the  knees  and 
upper  portion  of  the  foot  of  the  cow,  frequently  crawl- 
ing from  them  to  the  hands  of  the  veterinary,  but  their 
bites  had  no  bad  effect  on  him.  It  would  seem  from 
this  as  though  animals  are  more  susceptible  than  man. 

This  biting  fly  has  often  been  thought  to  be  a  dis- 
ease carrier  and  especially  of  blood  parasites  of  do- 
mestic animals.  The  evidence  for  and  against  has  been 
carefully  considered  by  Austen  (1909,  p.  153),  who 


246    THE  HOUSE  FLY— DISEASE  CARRIER 

summarizes  his  conclusions  in  the  following  words : 
"It  may  be  regarded  as  proved  that  Stomoxys  calcitrant 
L.,  as  also  S.  nigra,  Macq.,  and  probably  other  species 
of  the  genus,  can  convey  trypanosomes  directly  from 
an  infected  to  a  healthy  animal,  when  the  bites  follow 
one  another  immediately.  On  the  other  hand,  the  evi- 
dence tends  to  show  that  when  the  interval  between 
the  bites  is  longer  (the  maximum  period  within  which 
a  bite  is  infectious  has  not  yet  been  determined),  al- 
though active  trypanosomes  may  be  present  in  the  in- 
testine of  the  fly,  its  life  is  innocuous.  There  is  no 
indication  that  trypanosomes  ingested  by  5".  calcitrant 
pass  through  a  developmental  cycle,  and  they  appar- 
ently disappear  within  twenty-four  hours.  With  re- 
gard to  diseases  other  than  trypanosomiases,  there  are 
some  grounds  for  thinking  that  S.  calcitrans,  like  other 
biting  flies,  may  occasionally  disseminate  the  bacillus 
of  anthrax,  and,  in  Europe,  it  would  appear  that  the 
fly  is  the  intermediate  host  of  a  species  of  Filaria  para- 
sitic in  cattle. 

THE  LITTLE  HOUSE  FLY 
(Fannia  [Homalomyia]  canicularis  L.) 

In  discussing  the  size  of  the  adult  house  fly  in  Chap- 
ter I,  we  mentioned  this  little  fly  which  is  found  rather 
commonly  upon  window-panes  in  houses,  and  stated 
that  it  was  the  source  of  the  prevalent  error  to  the 
effect  that  house  flies  grow  after  they  become  winged 
and  that  these  little  flies  are  the  young  of  the  larger 
flies.  They  belong,  however,  not  only  to  an  entirely 


Fig.  24. — The  little  house  fly  (Homalomyia  brevis}  ;  antennae  and  larva 
at  right;  greatly  enlarged.     (Author's  illustration.) 


Fig.  25. — The  stable  fly   (Muscina  stabulans)  ;  larva  at  right;  greatly 

enlarged.    Anatomical  details  b,  c,  d,  e,  g,  h,  i,  still  more 

enlarged.     (Author's  illustration.) 


THE  LITTLE  HOUSE  FLY  247 

distinct  species  but  to  a  different  family,  these  little 
ones  being  members  of  the  family  Anthomyidae.  There 
are  several  of  these  species  of  Homalomyia,  including 
not  only  canicularis,  but  H.  brevis  Rond.  and  H. 
scalaris  Fab.,  but  canicularis  is  the  one  found  most 
abundantly  in  houses.  The  name  "little  house  fly"  has 
not  been  definitely  applied  to  it  in  this  country,  but 
it  is  a  translation  of  the  German  popular  name,  "Kleine 
Stubenfliege."  The  larvae  of  this  species  live  in  de- 
caying vegetable  material  and  have  also  been  found 
living  in  dead  insects  of  different  kinds.  They  have 
even  been  found  in  the  nests  of  the  common  bumble- 
bee. They  will  breed  also  in  excreta  of  animals  and 
in  human  excreta,  and  therefore  would  be  quite  as 
dangerous  as  the  true  house  fly  were  they  as  numerous. 
They  make  their  appearance  early  in  the  summer  and 
persist  until  autumn. 

The  allied  species,  H.  brevis,  is  not  so  common  in 
houses  as  the  one  just  mentioned,  but  it  is  an  abundant 
breeder  in  human  excrement. 

Both  species  are  rapid  breeders,  and  a  generation  is 
produced  every  two  weeks,  in  the  vicinity  of  Wash- 
ington, in  summer.  The  full  development  has  not  been 
traced,  but  the  larvae  are  quite  different  from  the  larvae 
of  the  house  fly.  That  of  brevis  is  shown  in  Fig.  24. 
It  and  its  relatives  are  all  furnished  with  a  double  row 
of  spiny  processes  on  either  side,  giving  them  a  very 
characteristic  appearance.  Their  larvae  have  occa- 
sionally been  found  in  freshly  passed  human  dejecta 
and  are  surely  on  occasion  voided  by  persons  who  have 


248    THE  HOUSE  FLY— DISEASE  CARRIER 

probably    swallowed    them    with    uncooked   vegetable 
food. 

THE  STABLE  FLY  (Muscina  stabulans  Fall.) 

This  is  one  of  the  flies  which  very  much  resemble 
the  house  fly,  and  is  frequently  mistaken  for  it.  It  be- 
longs to  the  same  family  and  is  of  the  same  general 
color.  It  is  not  so  abundant  in  houses  as  some  of  the 
others  we  have  mentioned.  In  1900,  out  of  the  23,087 
flies  collected  in  dining-rooms  and  kitchens  in  different 
parts  of  the  country,  thirty-seven  belonged  to  this  spe- 
cies. It  is  common  throughout  Europe,  everywhere  in 
the  United  States,  and  extends  south  to  Argentina. 
In  England  it  is  said  to  be  found  in  and  near  houses. 
Hewitt  has  found  it  occurring  in  early  summer  before 
the  house  fly  has  appeared  in  great  numbers.  It  is 
somewhat  larger  than  the  true  house  fly,  and  is  well 
shown  in  the  accompanying  figure,  which  also  shows 
some  of  the  structural  details  of  both  the  adult  and  the 
larva.  The  adult  may  be  at  once  distinguished  from 
the  house  fly  by  the  gradual  curve  of  the  vein  reaching 
the  tip  of  the  wing,  instead  of  the  abrupt  angle  in  the 
same  vein  in  the  house  fly. 

The  larvae  of  the  stable  fly  live  upon  decaying  sub- 
stances, fungi,  etc.,  but  it  is  recorded  in  Europe  as 
feeding  upon  caterpillars  and  larval  bees.  Schiner 
states  that  it  breeds  in  cow  dung,  and  it  has  also  been 
found  in  dead  animals.  In  this  country  it  feeds  upon 
the  dead  chrysalids  of  insects,  and  has  been  reared  from 
dying  squash  plants.  The  fly  has  also  been  reared  from 


THE  CHEESE  FLY 

masses  of  the  larvae  and  pupae  of  the  imported  elm 
leaf  beetle;  also  from  a  decaying  squash.  Aldrich  in 
Idaho  has  reared  it  from  rotting  radishes.  In  Wash- 
ington it  has  been  reared  from  human  excreta.  The 
complete  round  of  a  generation  is  said  to  occupy  from 
five  to  six  weeks.  (Fig.  25.) 

This  fly  is  one  of  the  dangerous  occasional  inhab- 
itants of  houses,  not  only  because  it  may  breed  in  hu- 
man excreta,  but  because  it  is  greatly  attracted  to  this 
substance  when  it  chances  to  be  deposited  in  the  open. 
There  seems  to  be  no  especial  reason  why  it  should  be 
called  the  stable  fly,  since  the  preferred  food  habits 
of  its  larvae  should  make  it  more  abundant  away  from 
stables,  and  its  scientific  name  stabulans  was  given  to 
it  by  Fallen  before  its  real  habits  were  known. 

It  is  interesting  to  note,  by  the  way,  that  the  larva 
of  the  fly  has  been  found  to  have  passed  through  the 
human  stomach,  to  which  it  had  probably  gained  en- 
trance through  the  eating  of  spoiled  vegetables. 

THE  CHEESE  FLY  (Piophila  casei  L.) 

The  little,  shining-black  flies  of  the  genus  Piophila 
breed  in  cheese,  ham,  chipped  beef,  and  other  fatty  or 
spoiled  and  decaying  animal  matter.  The  eggs  hatch 
into  small,  white,  cylindrical  maggots  which  feed  upon 
the  cheese  or  meat  and  rapidly  reach  full  growth,  at 
which  time  they  are  one-half  of  an  inch  in  length.  The 
maggot  is  commonly  called  the  cheese  skipper  or  the 
ham  skipper  from  its  wonderful  leaping  powers,  which 
it  possesses  in  common  with  certain  other  fly  larvae,  all 


250    THE  HOUSE  FLY— DISEASE  CARRIER 

of  which  lack  legs.  The  leap  is  made  by  bringing  the 
two  ends  of  the  body  together  and  suddenly  releasing 
them,  like  a  spring.  In  this  way  it  will  sometimes  jump 
three  or  four  inches.  The  species  is  cosmopolitan  at 
present,  and  it  was  doubtless  originally  imported  from 
Europe  into  the  United  States  in  old  cheeses. 

Careful  observations  have  been  made  on  the  life  his 
tory  of  this  fly  by  several  writers.  In  1892  Miss  Mary 
E.  Murtfeldt  studied  the  life  history  of  the  summer 
generation  in  a  western  packing  establishment.  She 
found  that  the  eggs  were  laid  in  rather  close  clusters 
of  from  five  to  fifteen,  and  were  also  deposited  singly. 
About  thirty  seem  to  have  been  laid  by  a  single  female. 
The  egg  is  white,  slender,  oblong,  slightly  curved,  one 
millimeter  in  length,  and  with  a  diameter  about  one- 
fourth  of  its  length.  It  hatches  in  about  thirty-six 
hours,  and  the  larva  completes  its  growth  in  from  seven 
to  eight  days,  reaching  a  length  of  seven  to  nine  milli- 
meters. Where  food  is  sufficient  the  larva  does  not 
move  about,  and  groups  of  them  will  sometimes  com- 
plete their  growth  in  the  same  crevice  in  which  the 
mother  fly  deposited  her  eggs.  When  full  grown,  how- 
ever, the  larva  moves  away  to  some  dry  spot,  contracts 
in  length,  assumes  a  yellowish  color,  and  gradually 
forms  into  a  golden-brown  puparium  four  or  five  milli- 
meters in  length.  The  adult  fly  issues  in  ten  days. 
Thus  three  weeks  may  complete  the  entire  life  cycle, 
in  August,  in  St.  Louis. 

In  Europe,  Kessler  found  that  the  average  summer 
duration  of  this  insect  is  four  to  five  weeks,  and  states 


Fig.  26. — The  cheese  fly  (Piophila  casei)  :  a,  larva  ;  b,  puparium  ;  c,  pupa; 
d,  adult  male;  e,  adult  female ;  all  enlarged.    (Author's  illustration.) 


Fig.    27.— The    fruit    fly    (Drosophila    ampelophila)  ;    a,    adult    male; 

b,  antennae ;  c,  fore  tibia ;  d,  e,  puparium ;  f,  larva ;  g,  anal  segment 

of  larva;  enlarged.     (Author's  illustration.) 


THE  FRUIT  FLIES  251 

that  the  larva  over-winters  in  the  puparium.  Other 
writers  say  that  the  insect  passes  the  winter  as  an  adult 
fly.  (Fig.  26.) 

In  this  country  this  fly  does  not  play  so  important 
a  part  as  a  cheese  insect  as  it  does  as  an  enemy  to 
smoked  meat.  It  seems  certain  that  the  mother  fly 
prefers  the  older  and  richer  cheeses  in  which  to  de- 
posit her  eggs.  Her  taste  is  excellent,  and,  while  it 
is  a  fair  thing  to  say  that  skippery  cheese  is  usually 
the  best,  it  will  hardly  do  to  support  the  conclusion 
that  it  is  good  because  it  is  skippery,  although  this  con- 
clusion is  current  among  a  certain  class  of  cheese  eaters. 

The  cheese  fly,  under  ordinary  circumstances,  is  not 
a  dangerous  species,  but  it  is  well  to  remember  that 
not  only  has  it  been  reared  from  dead  bodies,  but  that 
it  is  also  attracted  to  excreta  of  all  kinds. 

THE  FRUIT  FLIES  (Drosophila  ampelophila  Loew) 

The  minute  flies  of  the  family  Drosophilidse,  com- 
monly known  as  fruit  flies  or  pomace  flies,  are  attracted 
to  decaying  vegetation,  especially  to  fruit,  and  are  fre- 
quently found  in  houses  in  the  autumn  about  dishes 
containing  pears,  peaches,  and  grapes.  They  are  at- 
tracted to  fruit  both  for  food  and  for  places  to  lay 
their  eggs,  since  their  larvae  live  in  decaying  vegetable 
matter. 

The  commonest  of  the  fruit  flies  in  the  United  States 
is  Drosophila  ampelophila.  It  occurs  .also  in  the  West 
Indies  and  South  Europe.  It  does  considerable  dam- 
age to  canned  fruits  and  pickles,  breeds  in  decaying 


252    THE  HOUSE  FLY— DISEASE  CARRIER 

apples  and  the  refuse  of  cider  mills  and  fermenting 
vats  of  grape  pomace.  It  is  a  rather  rapid  breeder, 
and  a  generation  may  develop  in  twenty  days,  more  or 
less.  It  is  attracted  especially  to  preserves  and  canned 
goods,  and  frequently  damages  raspberry  vinegar.  It 
is  often  very  difficult  to  prevent  the  fly  from  entering 
fruit  jars. 

There  are  about  thirty  species  of  Drosophila  in 
North  America,  and  the  majority  of  them  breed  in 
the  juices  of  decaying  and  fermenting  fruit.  Aside 
from  the  one  just  mentioned,  D.  amocna,  D.  funebris, 
D.  graminum,  and  D.  transversa  are  occasionally  found 
in  houses.  Another  species,  D.  cellaris,  occurs  in  cel- 
lars in  fermenting  liquids,  such  as  wine,  cider,  vinegar, 
and  beer;  also  in  decaying  potatoes.  Another  species 
damages  flour  paste ;  and  still  another  mustard  pickles. 
One  species,  D.  flaveola,  does  not  need  decaying  vege- 
tation for  its  larval  food,  since  its  larvae  mine  the  leaves 
of  cabbages  and  radishes. 

The  fruit  flies  may  be  dangerous  inhabitants  of 
houses,  since  they  are  nearly  all  attracted  to  excreta, 
and  some  of  them  breed  in  human  excrement.  The 
larva  and  puparium,  as  well  as  the  adult  fly  of  D. 
ampclophila,  are  shown  in  Fig.  27. 

THE  BLUEBOTTLE  OR  GREENBOTTLE  FLIES 

THE  BLOW  FLIES  (Calliphora  erythrocephala  Meig., 

Lucilia  ccesar  L.,  Phormia  terranovce  Desv.) 

Several  species  of  bluebottle  or  greenbottle  flies  oc- 
casionally gain  entrance  to  houses,  and  all  are  danger- 


THE  BLOW  FLIES  253 

ous  species  and  liable  to  carry  intestinal  diseases.  Their 
larvae  as  a  rule  feed  in  excreta  or  in  decaying  flesh,  but 
a  bluebottle  fly  in  a  milk  jug  is  no  more  dangerous 
than  a  house  fly  in  the  same  situation. 

Lucilia  ceesar  L.  (Fig.  28)  is  a  common  and  wide- 
spread form,  abundant  in  both  Europe  and  North 
America,  and  is  one  of  several  species  of  the  shining 
green  or  bluish  flies  commonly  found  about  dead  ani- 
mals and  different  kinds  of  excreta.  It  is  not  ordinarily 
found  in  houses,  but  may  be  driven  in  at  the  approach 
of  a  heavy  storm,  just  as  is  the  case  with  the  biting 
house  fly.  On  May  17,  1899,  for  example,  a  heavy 
storm  occurred  about  four  P.M.,  and  the  next  morning 
twenty-eight  specimens  of  this  species  were  found  to 
have  come  into  one  of  the  rooms  of  my  office.  In 
Europe  L.  ccesar  is  known  as  the  "greenbottle  fly,"  and 
is  almost  exclusively  a  carrion  feeder. 

Calliphora  erythrocephala  Meig.  (Fig.  29)  is  an- 
other widespread  species  common  to  Europe  and  North 
America.  It  is  a  large  bluebottle  fly  of  rather  dull 
color  with  black  spines  on  the  thorax.  It  is  the  com- 
mon blow  fly  of  Europe  and  is  the  species  treated  by 
Lowne  in  his  classic  work  on  the  anatomy  of  the  blow 
fly.  Its  larvae  are  indistinguishable  from  those  of  the 
greenbottle  fly.  The  eggs  are  laid  on  meat  and  dead 
animals  and  even  upon  dead  insects.  The  species  is 
unusual  from  the  enormous  number  of  eggs  laid  by  a 
single  female.  The  Russian  author,  Porchinsky,  re- 
cords from  450  to  600  eggs  from  a  single  female. 
Hewitt  records  the  duration  of  a  single  generation  as 


254    THE  HOUSE  FLY— DISEASE  CARRIER 

from  twenty-two  to  twenty-three  days.  This  blow  fly 
is  a  characteristically  out-of-door  fly,  but  under  cer- 
tain circumstances  may  be  found  in  houses  in  some 
numbers.  In  October,  1899,  f°r  example,  a  gentleman 
living  in  the  suburbs  of  Washington  found  thousands 
of  these  flies  in  his  cellar.  No  cows  or  horses  were 
kept  near  the  house,  and  there  had  been  no  dead  ani- 
mals about  so  far  as  he  knew.  It  is  probable,  however, 
that  these  flies  had  come  from  some  dead  animal,  and 
had  sought  the  cellar  for  hibernating  purposes,  al- 
though the  weather  was  still  warm. 

Phormia  terr&novcc  Desv.  (Fig.  30.)  The  bluebot- 
tle fly  just  mentioned  is  a  rather- large  species.  The 
Phormia,  however,  is  a  medium-sized  or  rather  small 
bluebottle.  It  was  originally  described  from  New- 
foundland, but  is  widespread  in  the  United  States.  It 
is  occasionally  found  in  houses,  and  I  have  more  than 
once  seen  them  upon  window  panes.  It  is  abundantly 
attracted  to  human  excreta,  and  has  been  taken  under 
many  varying  conditions  about  Washington  :  enormous 
numbers  were  found  on  one  occasion  in  the  sinks  of  a 
deserted  militia  camp  at  Leesburg,  Virginia. 

THE  FLESH  FLIES  (Sarcophaga  assidna  Walk.) 

We  include  under  this  heading  the  flies  of  the  genus 
Sarcophaga,  on  account  of  the  significance  of  the  sci- 
entific name,  although  many  Sarcophagids  are  not  true 
flesh  eaters.  Several  of  them  very  closely  resemble 
the  house  fly,  and  some  of  them  are  sometimes  found 
in  houses.  The  common  widespread  flesh  fly  of  Europe 


Fig.  28. — Lucilia  casar ;  enlarged. 
(Author's  illustration.) 


Fig.  29. — Calliphora  erythrocephala 
enlarged.     (Author's   illustration.) 


Fig.  30. — Phonnia  terrccnovce;  en- 
larged.   (Author's  illustration.) 


Fig-  33- — Scatophaga  furcata;  en- 
larged.   (Author's  illustration.) 


THE  DUNG  FLIES  255 

and  Australia,  a  very  general  scavenger,  is  known  as 
Sarcophaga  carnaria  L.,  and  in  countries  which  it  in- 
habits is  once  in  a  while  found  in  houses.  It  does  not 
seem  to  occur  in  the  United  States,  although  a  species 
which  much  resembles  it,  S.  sarracenice  Riley,  is  abun- 
dant throughout  the  country.  It  looks  like  a  very  large 
and  active  house  fly,  and  is  occasionally  found  in 
houses.  It  is  commonly  reared  from  the  remains  of 
dead  insects,  but  is  also  attracted  to  and  breeds  in  ex- 
creta. (Fig.  31.) 

A  smaller  species,  5*.  assidua  Walk.,  much  resembles 
the  house  fly  and  is  of  about  the  same  size.  -  It  is  con- 
fined to  the  United  States  and  is  occasionally  found  in 
houses.  It,  like  the  preceding  species,  breeds  in  dead 
insect  remains,  but  is  attracted  to  and  breeds  in  ex- 
creta and  is  therefore  dangerous. 

THE  DUNG  FLIES     ' 
(Sepsis  violacea  Meig.,  Scatophaga  furcata  Say) 

There  is  a  little  black  fly  known  as  Sepsis  violacea 
Meig.,  which  is  shown  in  Fig.  32  and  which  is  not  at 
all  uncommon  in  houses,  being  found  as  a  rule  upon 
the  window  panes.  It  belongs  to  the  same  family  as 
the  cheese  fly,  but  does  not  attack  stored  foods  or  any- 
thing to  be  found  in  the  pantry.  It  breeds  almost  ex- 
clusively in  excreta  and  has  been  reared  in  swarms 
from  an  old  human  deposit  collected  on  the  Potomac 
flats  near  the  city  of  Washington.  It  is  very  small  in 
size,  glistening  black  in  color,  and  of  slender  shape. 

There  is  a  whole  family  of  small,  brownish  flies 


256    THE  HOUSE  FLY— DISEASE  CARRIER 

known  as  the  Scatophagidae,  which,  as  the  scientific 
name  indicates,  are  attracted  to  and  breed  in  the  dung 
of  different  animals,  and  also  to  some  extent  in  decay- 
ing vegetable  material.  They  are,  as  a  rule,  rather 
light-colored,  bristly  flies.  The  species  shown  at  Fig. 
33  is  known  as  Scatophaga  furcata  Say.  It  is  a  North 
American  species  of  rather  wide  distribution,  which 
in  its  early  stages  lives  in  all  sorts  of  excreta  and  is 
once  in  a  great  while  found  in  houses.  It  does  not 
hibernate  as  an  adult  fly,  but  in  its  puparia  in  dung. 

THE  MOTH  FLIES  (Psychoda  minuta  Banks) 

There  are  certain  very  minute  flies  belonging  to  a 
family  known  as  the  Psychodidae,  which  are  very  pe- 
culiar from  the  fact  that  they  resemble  little  moths, 
their  broad  wings  being  covered  with  hairs,  making 
them  look  like  moths.  They  are  very  weak  fliers,  and 
are  frequently  found  upon  windows  and  on  the  under 
surfaces  of  leaves.  They  are  so  small  and  fragile  that 
they  are  difficult  to  capture  and  preserve.  What  they 
do  in  houses  no  one  knows,  unless  possibly  they  enter 
them  for  protection.  The  larvae  of  some  species  breed 
in  excreta;  others  in  decaying  vegetation,  and  still 
others  in  water,  sewage-polluted  water  being  preferred. 
Psychoda  minuta  Banks  has  been  reared  from  cow 
dung  at  Washington.  None  of  the  North  American 
species  has  the  blood-sucking  habit,  although  a  genus 
(Phlcebotomus)  which  occurs  in  Southern  Europe  and 
in  other  parts  of  the  world  bites  human  beings  and 
has  been  accused  of  disease-carrying  probabilities. 


Fig.  31. — Sarcophaga  assidua;  larva  at  right,  puparium  at  left;  enlarged. 
(Author's  illustration.) 


Fig.  32. — Sepsis  violacea;  puparium  at  left;  enlarged  antennae  at  upper 
right;  enlarged.     (Author's  illustration.) 


THE  HUMPBACK  FLIES 


257 


THE  HUMPBACK  FLIES 

The  humpback  flies  of  the  family  Phoridse  need  not 
be  mentioned  here  especially,  except  for  the  fact  that 
one  of  the  species,  Hypocera  (Phora)  femorata,  occurs 
occasionally  in  houses,  and  possibly  others  of  the  family 


Fig.  34. — Phora  femorata;  greatly  enlarged.    (Original.) 

may  also  be  found  from  time  to  time  in  domiciles.  In 
the  collection  of  flies  made  in  houses  in  1900  there 
were  thirty-three  specimens  of  P.  femorata  out  of  the 
23,087  flies  captured.  The  larval  habits  of  this  par- 


258    THE  HOUSE  FLY— DISEASE  CARRIER 

ticular  species  are  not  known,  but  its  relatives  feed  in 
the  earlier  stages  on  decaying  vegetable  matter,  dead 
insects,  snails,  etc.  The  species  in  question  possibly- 
fed  upon  decaying  vegetation  in  the  neighborhood  of 
the  houses  in  which  it  was  collected. 

THE  WINDOW  FLIES  (Scenopinus  fenestralis  L.) 

Comstock  has  applied  the  term  window  flies  to  the 
little  flies  of  the  family  Scenopinid?e.  The  term,  how- 
ever, does  not  apply  to  all  of  them ;  but  the  best-known 


Fig.  35.— Scenopinus  fenestralis;  a,  adult;  b,  pupa;  c,  larva; 
d,  eggs ;  enlarged.     (Original.) 

species,  namely,  Scenopimts  fenestralis,  is  not  uncom- 
monly found  upon  windows  both  in  this  country  and 
in  Europe.  These  flies  are  usually  black  and  rather 
smooth,  S.  fenestralis  being  about  one  quarter  of  an 


THE  WINDOW  FLIES  259 

inch  long.  It  has  a  humpbacked  appearance,  and  the 
abdomen  is  flattened.  Osten  Sacken  (1886)  has  given 
a  good  review  of  the  European  literature  on  the  habits 
of  this  fly,  and  has  shown  that  it  has  been  reared  from 
decaying  tree  fungi,  from  horse  hair  in  a  mattress, 
from  a  swallow's  nest,  from  the  cocoon  of  a  large  moth, 
from  carpets,  from  a  branch  of  a  tree,  from  pine  boards, 
from  the  pupa  of  a  large  moth,  and  from  a  root  of 
aconite. 

The  different  European  authors  making  these  obser- 
vations from  time  to  time  have  thought  variously  that 
the  window  fly  was  carnivorous  or  vegetarian,  in  ac- 
cordance with  the  substances  from  which  they  reared 
it.  Osten  Sacken,  however,  concludes  rather  positively 
that  it  is  carnivorous,  that  the  larva  does  not  frequent 
fungi,  rotten  wood,  swallows'  nests,  etc.,  for  the  sake 
of  vegetable  material  or  animal  remains,  but  for  the 
sake  of  the  pupae  and  perhaps  also  of  the  larvae  which 
it  finds  there.  He  deduces  from  this  that  when  it  oc- 
curs in  carpets  and  horse  hair,  it  is  not  because  it  feeds 
on  them,  but  because  it  hunts  there  for  the  larvae  and 
pupae  of  the  moths  or  other  insects  that  live  in  them. 

Similarly  in  this  country  divers  observations  have 
been  made,  and  the  records  of  the  Bureau  of  Entomol- 
ogy at  Washington  show  that  it  has  been  reared  from 
strawberry  plants,  from  the  egg-pods  of  grasshoppers, 
from  the  hair  of  a  Navajo  blanket,  from  a  sack  of  rye 
infested  with  the  grain  beetle,  from  under  carpets, 
among  stored  oats  and  stored  corn,  from  a  basket  con- 
taining small  rolls  of  cotton  and  woolen  goods,  and 


260    THE  HOUSE  FLY— DISEASE  CARRIER 

from  the  seeds  of  sugar  beets  stored  in  a  mill;  also 
from  larva?  found  with  other  larva?  on  the  roots  of  roses, 
as  well  as  from  under  the  bark  of  a  post-oak  pole.  Ex- 
act observations  have  been  made  here  showing  that  the 
larva  is  undoubtedly  carnivorous :  it  has  been  fed  upon 
the  larvae  of  stored  grain  insects,  and  when  found  in 
woolen  goods  and  under  carpets  it  is  undoubtedly  in 
search  of  clothes  moths  upon  which  to  feed. 

The  larva  is  long,  white,  and  snake-like  in  shape, 
with  a  dark  head.  It  apparently  has  many  segments  to 
the  body,  since  each  of  the  abdominal  segments  is  di- 
vided by  a  strong  constriction.  In  feed  stores  the  flies 
are  nearly  always  to  be  found  around  the  windows, 
and  the  probability  is  very  strong  that  they  feed  upon 
such  small  soft-bodied  creatures  as  flour  mites  and 
beetle  larvae. 

Nothing  definite  has  been  ascertained  concerning  the 
duration  of  the  different  stages,  but  from  larvae  taken 
in  January  adults  issued  in  April,  and  from  larvae  re- 
ceived April  1 8th  adults  issued  on  the  Qth  of  June; 
with  larvae  received  August  6th,  one  changed  to  pupa 
on  August  25th,  another  on  August  29th,  the  flies  issu- 
ing September  loth  and  I2th  respectively. 

It  is  a  pleasure  to  state  that  at  least  one  of  the  flies 
found  in  houses  is  probably  beneficial  rather  than  in- 
jurious, and  that  this  species  is  Scenopinus  fenestralis. 


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268    THE  HOUSE  FLY— DISEASE  CARRIER 

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APPENDIX  I 

FLIES  FREQUENTING  HUMAN  DEJECTA  AND  THOSE 
FOUND  IN  KITCHENS 

IN  summing  up  the  results  of  the  work  carried  on 
by  the  writer,  the  number  of  species  of  insects  found 
breeding  in  or  frequenting  human  excrement  was  very 
large.  There  were  many  coprophagous  beetles — forty- 
four  species  in  all — and  many  Hymenopterous  para- 
sites, all  of  the  latter  having  probably  lived  in  the  lar- 
val condition  in  the  larvae  of  Diptera  or  Coleoptera 
breeding  in  excrement.  Neither  the  beetles  nor  the 
Hymenoptera,  however,  have  any  importance  from  the 
disease-transfer  standpoint.  The  Diptera  alone  were 
the  insects  of  significance  in  this  connection.  Of  Dip- 
tera there  were  studied  in  all  seventy-seven  species,  of 
which  thirty-six  were  found  to  breed  in  human  feces, 
while  the  remaining  forty-one  were  captured  upon  such 
excrement.  The  following  list  indicates  the  exact  spe- 
cies arranged  under  their  proper  families.  The  paren- 
thetical remarks  after  each  species  should  be  estimated 
in  the  following  order,  from  "scarce"  to  "extremely 
abundant" :  scarce,  rather  scarce,  not  abundant,  mod- 
erately abundant,  abundant,  very  abundant,  extremely 
abundant. 

273 


274    THE  HOUSE  FLY— DISEASE  CARRIER 

REARED  (USUALLY  ALSO  CAPTURED) 

FAMILY  CHIRONOMID^: 
I.  Ceratopogon  sp.  (scarce). 

FAMILY  BIBIONID^E 

2..  Scatopse  pulicaria  Loew  (moderately  abundant). 
FAMILY  EMPIDID^: 

3.  Tachydromia  sp.  (rather  scarce). 

FAMILY  DOLICHOPODID.E 

4.  Diaphorus  leucostomus  Loew  (scarce). 

5.  Diaphorus  sodalis  Loew  (not  abundant). 

FAMILY  SARCOPHAGIOE 

6.  Lucilia  caesar  L.  (abundantly  captured;  one  reared), 

7.  Sarcophaga  sarraceniae  Riley  (abundant). 
8. ' Sarcophaga  assidua  Walker  (abundant). 
9.  Sarcophaga  trivialis  V.  d.  W.  (abundant). 

10.  Helicobia  quadrisetosa  Coq.  (very  abundant). 

FAMILY  MUSCID^: 

11.  Musca  domestica  L.  (abundant). 

12.  Morellia  micans  Macq.   (abundant). 

13.  Muscina  stabulans  Fall,  (abundant). 

14.  Myospila  meditabunda  Fabr.  (abundant). 

FAMILY  ANTHOMYHXE 

15.  Homalomyia  brevis  Rondani  (very  abundant). 

16.  Homalomyia  canicularis  L.   (moderately  abundant) 

17.  Homalomyia  scalaris  Fabr.  (scarce). 

18.  Hydrotaea  dentipes  Meig.  (moderately  abundant). 

19.  Limnophora  arcuata  Stein  (moderately  abundant). 

20.  Ophyra  leucostoma  Wied.  (abundant). 

21.  Phorbia  cinerella  Fall,  (abundant). 

22.  Phorbia  fusciceps  Zett.   (moderately  abundant). 


APPENDIX  I  275 

FAMILY  ORTALID^: 

23.  Euxesta  notata  Wied.   (moderately  abundant). 

FAMILY  LONCH^ID^E 

24.  Lonchsea  polita  Say  (moderately  abundant). 

FAMILY  SEPSID.E 

25.  Sepsis  violacea  Meig.  (extremely  abundant). 

26.  Nemopoda  minuta  Wied.  (very  abundant). 

FAMILY  DROSOPHILID^: 

27.  Drosophila  ampelophila  Loew  (moderately  abundant). 

FAMILY  OSCINID^E 

28.  Oscinis  trigramma  Loew  (rather  scarce). 

FAMILY  AGROMYZID^E 

29.  Ceratomyza  dorsalis  Loew  (rather  scarce). 

30.  Desmometopa  latipes  Meig.  (rather  scarce). 

FAMILY  EPHYDRID^E 

31.  Scatella  stagnalis  Fall,  (scarce). 

FAMILY  BORBORID^E 

32.  Limosina  albipennis  Rond.   (very  abundant). 

33.  Limosina  fontinalis  Fall,  (very  abundant). 

34.  Sphaerocera  pusilla  Meig.  (abundant). 

35.  Sphserocera  subsultans  Fabr.  (very  abundant). 

FAMILY  SCATOPHAGID^: 

36.  Scatophaga  furcata  Say  (very  abundant). 

CAPTURED   (NOT  REARED) 

FAMILY  CHIRONOMHXE 

1.  Chironomus  halteralis  Coq.  (scarce). 

FAMILY  TIPULID^: 

2.  Limnobia  sciophila  O.  S.  (scarce). 


276    THE  HOUSE  FLY— DISEASE  CARRIER 

FAMILY  EMPIDHXE 

3.  Rhamphomyia  manca  Coq.  (not  abundant). 

FAMILY  DOLICHOPODID^: 

4.  Neurigonia  tenuis  Loew  (scarce). 

FAMILY  SARCOPHAGID^: 

5.  Chrysomyia  macellaria  Fabr.  (rather  abundant). 

6.  Calliphora  erythrocephla  Meig.  (rather  abundant) 

7.  Sarcophaga  lambens  VVied.  (rather  scarce). 

8.  Sarcophaga  plinthopyga  Wied.  (rather  scarce). 

9.  Cynomyia  cadaverina  Desv.  (rather  scarce). 

10.  Phormia  terraenovae  Desv.  (very  abundant). 

FAMILY  MUSCHXE 

11.  Muscina  caesia  Meig.  (scarce). 

12.  Muscina  tripunctata  V.  d.  W.  (scarce). 

13.  Stomoxys  calcitrans  L.  (rather  abundant). 

14.  Pseudopyrellia  cornicina  Fabr.  (abundant). 

15.  Pyrellia  ochricornis  Wied.  (rather  scarce). 

FAMILY  ANTHOMYIID^E 

16.  Hylemyia  juvenalis  Stein  (rather  scarce). 

17.  Hydrotaea  metatarsata  Stein  (rather  scarce). 

18.  Coenosia  pallipes  Stein    (rather  scarce). 

19.  Mydaea  palposa  Walker  (rather  scarce). 

FAMILY  ORTALID.C 

20.  Rivellia  pallida  Loew  (rather  scarce). 

FAMILY  SEPSID^E 

21.  Piophila  casei  L.  (rather  scarce). 

FAMILY  DROSOPHILID^ 

22.  Drosophila  funebris  Meig.  (scarce). 

23.  Drosophila  busckii  Coq.   (scarce). 


APPENDIX  I  277 

FAMILY  OSCINIDJE 

24.  Hippelates  flavipes  Loew  (rather  scarce). 

25.  Oscinis  carbonaria  Loew  (moderately  abundant). 

26.  Oscinis  coxendix  Fitch  (scarce). 

27.  Oscinis  pallipes  Loew  (rather  scarce). 

28.  Elachiptera  costata  Loew  (moderately  abundant). 

FAMILY  EPHYDRID^: 

29.  Discocerina  parva  Loew  (rather  scarce). 

30.  Hydrellia  formosa  Loew  (rather  scarce). 

FAMILY  BORBORID^E 

31.  Borborus  equinus  Fall,  (very  abundant,  undoubtedly 

breeds  here  also). 

32.  Borborus  geniculatns  Macq.  (moderately  abundant). 

33.  Limosina  crassimana  Hal.  (abundant). 

FAMILY  SYRPHID^ 

34.  Syritta  pipiens  L.  (scarce). 

FAMILY  PHORHLE 

35.  Phora  femorata  Meig.  (scarce). 

FAMILY  SCATOPHAGID^E 

36.  Scatophaga  stercoraria  L.  (moderately  abundant). 

37.  Fucellia  fucorum  Fall,  (rather  scarce). 

FAMILY  MICROPEZID^E 

38.  Calobata  fasciata  Fabr.  (rather  scarce). 

39.  Calobata  antennipes  Say  (moderately  abundant). 

FAMILY  HELOMYZHLE 

40.  Leria  pectinata  Loew  (scarce). 

41.  Tephrochlamys  rufiventris  Meig.  (scarce). 

It  should  be  stated  here  that  this  list,  containing  as 
it  does  only  a  record  of  actual  observations,  should  by 
no  means  be  considered  as  indicating  definitely  the 
habits  of  the  species  or  their  relative  abundance  under 


278    THE  HOUSE  FLY— DISEASE  CARRIER 

other  conditions.  Thus  some  of  the  species  here  indi- 
cated as  scarce  in  connection  with  excrement  may  be 
very  common  under  other  conditions,  which  would 
indicate  that  their  occurrence  upon  excrement  was  more 
or  less  accidental.  Moreover,  certain  of  the  species 
which  have  been  captured  on  excrement,  but  not  reared 
from  it,  are  nevertheless  undoubtedly  excrement  breed- 
ers, as  will  be  proved  by  future  observations.  Thus 
we  have  in  several  cases  certain  species  which  have  been 
reared  while  congeneric  species  have  simply  been  cap- 
tured, as,  for  example,  Nos.  7  and  8  of  the  captured 
species  are  congeneric  with  7,  8  and  9  of  the  reared 
series;  n  and  12  of  the  captured  series  are  congeneric 
with  13  of  the  reared  series;  17  of  the  captured  series 
is  congeneric  with  18  of  the  reared  series;  22  and  23 
of  the  captured  series  are  congeneric  with  27  of  the 
reared  series;  25,  26  and  27  of  the  captured  series  are 
congeneric  with  28  of  the  reared  series ;  33  of  the  cap- 
tured series  is  congeneric  with  32  and  33  of  the  reared 
series,  and  is  undoubtedly  an  excrement  breeder,  and 
the  same  may  be  said  of  36  of  the  captured  series  which 
is  congeneric  with  36  of  the  reared. 

From  these  data  it  will  be  noticed  that  the  most 
abundant  species  reared  were  Helicobia  quadrisetosa, 
Sepsis  violacea,  Nemopoda  minuta,  Limosina  albipen- 
nis,  Limosina  fontinalis,  Spharoccra  subsnltans,  and 
Scatophaga  furcata,  while  the  most  abundant  forms 
captured  on  excrement  were  Phorbia  terranovcu  and 
Borborus  equinus.  It  will  also  be  noticed  that  among 
the  reared  forms  there  are  ten  others  which  are  simply 


APPENDIX  I  .  279 

entered  as  "abundant,"  and  among  the  captured  two 
others.  With  these  facts  in  mind  we  are  prepared  to 
examine  the  results  of  the  kitchen  and  dining-room 
captures. 

The  results  so  far  stated  have  a  distinct  entomolog- 
ical interest  as  regards  the  exact  food  habits  of  a  large 
number  of  species,  many  of  the  observations  being 
novel  contributions  to  previous  knowledge  of  these 
forms;  but  the  practical  bearing  of  the  work  is  only 
brought  out  when  we  consider  which  of  these  forms 
are  likely  from  their  habits  actually  to  convey  disease 
germs  from  the  excrement  in  which  they  have  bred,  or 
which  they  have  frequented,  to  substances  upon  which 
people  feed.  Therefore  collections  of  the  Dipterous 
insects  occurring  in  kitchens  and  pantries  were  made, 
with  the  assistance  of  correspondents  and  observers  in 
different  parts  of  the  country,  all  through  the  summer 
of  1899  and  also  in  the  summer  and  autumn  of  1900. 
Such  collections  were  made  in  the  States  of  Massachu- 
setts, New  York,  Pennsylvania,  District  of  Columbia, 
Virginia,  Florida,  Georgia,  Louisiana,  Nebraska,  and 
California.  Nearly  all  of  the  flies  thus  captured  were 
caught  upon  sheets  of  the  ordinary  sticky  fly  paper, 
which,  while  ruining  them  as  cabinet  specimens,  did 
not  disfigure  them  beyond  the  point  of  specific  recog- 
nition. The  others  were  captured  in  the  ordinary  man- 
ner. 

In  all  there  were  examined  23,087  flies,  which  had 
been  caught  in  rooms  in  which  food  supplies  were  or- 
dinarily exposed ;  and  they  may  safely  be  said  to  have 


280    THP  HOUSE  FLY— DISEASE  CARRIER 

been  attracted  by  the  presence  of  these  food  supplies. 
Of  these  23,087  flies,  22,808  were  Mitsca  domestica, 
i.  e.,  ninety-eight  and  eight-tenths  per  cent,  of  the  whole 
number  captured.  The  remainder,  consisting  of  one 
and  two-tenths  per  cent,  of  the  whole,  comprised  vari- 
ous species,  the  most  significant  ones  being  Hornalomyia 
canicularis  (the  species  ordinarily  called  the  "little 
house  fly")  of  which  eighty-one  specimens  were  cap- 
tured; the  stable  fly  (Muscina  stabulans),  thirty-seven 
specimens;  Phora  femorata,  thirty-three;  Liicilia  cccsar, 
eighteen;  Drosophila  ampelophfta,  fifteen;  Sarcophaga 
trivialis,  ten ;  Calliphora  crythroccphala,  seven.  Mnsca 
domestica  is,  therefore,  the  species  of  great  significance. 
Homalomyia  canicularis  is  important.  Muscina  stabu- 
lans  is  of  somewhat  lesser  importance.  Drosophila 
anipclophila  is  an  important  form,  and  had  more  of  the 
captures  been  made  in  the  autumn  its  numbers  would 
probably  have  been  greater,  since  beyond  doubt  it  is 
an  abundant  species  in  houses  after  fruit  has  begun  to 
make  its  appearance  (say,  in  August  and  September 
and  on  until  winter  time)  in  pantries  and  on  dining- 
room  sideboards.  The  Calliphora  and  the  Lucilia  are 
of  slight  importance,  not  only  on  account  of  their  rar- 
ity in  houses,  but  because  they  are  not  true  excrement 
insects.  Other  forms  were  taken,  but  either  their 
household  occurrence  was  probably  accidental,  or  from 
their  habits  they  have  no  significance  in  the  disease- 
transfer  function. 

— Extracted  from :  A  Contribution  to  the  Study  of  the  Insect 
Fauna  of  Human  Excrement.     By  L.  O.  Howard  (p.  547). 


APPENDIX  II 
ON  SOME  FLIES  REARED  FROM  Cow  MANURE* 

IN  the  summer  of  1889,  while  engaged  in  an  investi- 
gation of  the  habits  and  life  history  of  the  horn  fly 
of  cattle  (Hcematobia  serrata),  the  writer  at  various 
times  brought  to  Washington,  from  different  points 
in  Virginia,  large  quantities  of  cow  manure  collected 
in  the  field,  and  eventually  succeeded  in  working  out 
the  complete  life  history  of  the  horn  fly,  as  displayed 
in  Insect  Life,  Vol.  II,  No.  4,  October,  1889.  In  this 
article  the  statement  is  made,  in  concluding,  that  the 
observations  were  greatly  hindered  and  rendered  dif- 
ficult by  the  fact  that  fresh  cow  dung  is  the  nidus  for 
a  number  of  species  of  Diptera,  some  about  the  same 
size  and  general  appearance  as  the  horn  fly,  and  that 
no  less  than  twenty  distinct  species  of  flies  had  been 
reared  from  horse  and  cow  dung,  mainly  the  latter, 
and  six  species  of  parasitic  insects  as  well.  The  plan 
finally  adopted  of  securing  the  isolation  of  the  horn 
flies  was  to  remove  the  eggs  from  the  surface  of  the 
dung  and  place  them  with  dung  which  was  absolutely 
fresh  and  collected  practically  as  it  fell  from  the  cow. 
A  report  upon  trie  other  species  was  promised,  but  was 
never  published,  although  Professor  Riley,  in  his  re- 

*Reprinted  from  an  article  with  this  title,  by  L.  O.  Howard, 
published  in  the  Canadian  Entomologist,  Vol.  33  (1901),  pp.  42-44. 

281 


282    THE  HOUSE  FLY— DISEASE  CARRIER 

port  for  1890,  listed  eight  parasites,  only  two  of  which 
were  specifically  determined. 

The  writer's  recent  investigations  of  the  insect  fauna 
of  human  excrement  (Proc.  Wash.  Acad.  of  Sciences, 
Vol.  II,  pp.  541-604.  Dec.  28,  1900)  aroused  his  in- 
terest in  the  general  subject  of  coprophagous  insects, 
and  the  flies  reared  in  1889-90,  from  cow  dung,  were 
looked  up  and  have  been  named  by  Mr.  D.  W.  Coquil- 
lett.  The  list  is  so  interesting  that  it  should  be  re- 
corded. It  will  be  noticed  that  several  of  the  species 
are  identical  with  those  found  breeding  in  human  ex- 
crement. These  are:  Sarcophaga  inccrta,  Helicobia 
quadrisetosa,  Musca  domestica,  Morellia  micans,  My- 
ospila  meditabunda,  Ophyra  leucostoma,  Sepsis  viola- 
cea,  Splicer ocera  subsultans  and  Limosina  albipouiis. 
The  rearing  of  Ceratopogon  spccularis  from  cow  dung 
is  of  especial  interest,  since,  down  to  the  record  in  the 
Washington  Academy  paper  just  referred  to,  no  in- 
sects of  this  genus  had  been  found  to  be  coprophagous. 
Some  of  the  other  records  are  interesting  for  the  same 
reason.  The  list  follows: 

FAMILY  CECIDOMYIIXE 

Diplosis,  sp.  Issued  Dec.  26,  1889;  and  Jan.  18,  1890; 
4  specimens. 

FAMILY  MYCETOPHILIOE 
Sciara,  sp.    Issued  March  26  and  29,  1890;  2  specimens. 

FAMILY  CHIRONOMID^: 

Camptocladius  bvssinus,  Schrank.  Issued  Jan.  2,  1890. 
Issued  Dec.  31,  1889;  and  March  25,  1890;  9  speci- 
mens. 


APPENDIX  II  283 

Camptocladius  minimus,   Meigen.     Issued  Dec.   23,   26, 

27.  30  and  31,  1889;  Jan.  13,  18,  and  March  25,  1890; 

12  specimens. 
Ceratopogon  specularis,   Coq.     Issued  August  28,   1889. 

Issued  Dec.  30,  1889;  6  specimens. 
Psychoda  minuta,   Banks.     Issued  Dec.  26,  30  and  31, 

1889;  and  Jan.  u,  1890;  4  specimens. 

FAMILY  RHYPHID^E 

Rhy films  punctatus,  Fabr.  Issued  Sept.  2,  3,  and  4,  1889. 
Issued  Jan.  13,  16,  18,  20,  22,  24  and  29,  Feb.  i, 
March  26  and  29,  and  April  5  and  9,  1890;  64  speci- 
mens. 

FAMILY  SARCOPHAGID^: 

Sarcophaga  incerta,  Walker.  Issued  Aug.  31,  1889.  Is- 
sued Aug.  30,  1889;  7  specimens. 

Sarcophaga,  sp.    Issued  April  23,  1890;  i  specimen. 

Helicobia  quadrisetosa,  Coq.  Issued  Aug.  6  and  30,  1889 ; 
2  specimens. 

Pollenia  rudis,  Fabr.     Issued  Dec.  23,  1889;  i  specimen. 

FAMILY  MUSCID^: 

Musca  domestica,  Linne.  Issued  Aug.  30  and  Sept.  2  and 
4,  1889 ;  20  specimens. 

Morellia  micans,  Macq.  Issued  Aug.  30,  1899.  Issued 
Dec.  23,  26.  27,  28,  30  and  31,  1889;  Jan.  2,  6,  8,  9, 
10,  n,  13,  14,  16,  17,  18,  20,  25  and  27,  Feb.  i, 
March  25,  April  5  and  9,  1890;  125  specimens. 

Myospila  meditabunda,  Fabr.  Issued  Aug.  26,  28,  29,  30, 
Dec.  23,  1889;  Jan.  9,  March  25,  26,  April  2,  9,  14, 
15,  1890.  Issued  April  5,  1890;  48  specimens. 

Hcematobia  serrata,  Desv.    Sept.  17,  2  specimens. 

FAMILY  ANTHOMYHXS 

Hydro  fcea  armipes.  Fallen.  Issued  Sept.  27,  30,  Oct.  4, 
1889;  Jan.  2,  6,  7,  8,  9,  10,  April  24,  1890;  38  speci- 
mens. 


284    THE  HOUSE  FLY— DISEASE  CARRIER 

Ophyra  leucostoma,  Wied.  Issued  Sept.  6,  1889;  u 
specimens. 

Limnophora,  sp.    Issued  Aug.  30,  31,  1889;  5  specimen^. 

Cccnosia  lata,  Walker.    Issued  April  25,  1890;  i  specimen. 

Ccenosia  ftavicoxa,  Stein.  Issued  Aug.  31,  1889;  4  speci- 
mens. 

Phorbia,  sp.    Issued  March  29,  1890;  I  specimen. 

FAMILY  SEPSID^E 

Sepsis  violacca,  Meigen.  Issued  Aug.  28,  1889;  8  speci- 
mens. 

FAMILY  BORBORID^ 
Sphfcrocera  siibsultans,  Fabr.     Issued  Aug.  30,  1889;  7 

specimens. 

Limosina  albipennis,  Rondani.  Issued  August  28,  Dec. 
23,  1889;  2  specimens. 


APPENDIX  III 

REGULATIONS  OF  THE  HEALTH  DEPARTMENT  OF  THE 
DISTRICT  OF  COLUMBIA  RELATING  TO  HOUSE  FLIES 

EXTRACT  from  An  Ordinance  to  Revise,  Consol- 
idate, and  Amend  the  Ordinances  of  the  Board 
of  Health,  etc.,  as  Amended  by  Commissioners'  Orders. 
SEC.  3.  That  manure,  accumulated  in  great  quan- 
tities; manure,  offal,  or  garbage  piled  or  deposited 
within  300  feet  of  any  place  of  worship,  or  of  any 
dwelling,  or  unloaded  along  the  line  of  any  railroad, 
or  in  any  street  or  public  way ;  cars  or  flats  loaded  with 
manure,  or  other  offensive  matter,  remaining  or  stand- 
ing on  any  railroad,  street  or  highway  in  the  cities 
of  Washington  or  Georgetown,  or  in  the  more  densely 
populated  suburbs  of  said  cities,  are  hereby  declared 
nuisances  injurious  to  health;  and  any  person  who 
shall  pile  or  deposit  manure,  offal,  or  garbage,  or  any 
offensive  or  nauseous  substance  within  300  feet  of  any 
inhabited  dwelling  within  the  limits  of  said  cities  or 
their  said  suburbs,  and  any  person  who  shall  unload, 
discharge,  or  put  upon  or  along  the  line  of  any  rail- 
road, street,  or  highway,  or  public  place  within  said 
cities  or  their  said  suburbs  any  manure,  garbage,  offal, 
or  other  offensive  or  nauseous  substance  within  300  feet 
of  any  inhabited  dwelling,  or  who  shall  cause  or  allow 
cars  or  flats  loaded  with  or  having  in  or  upon  them 

285 


286    THE  HOUSE  FLY— DISEASE  CARRIER 

any  such  substance  to  remain  or  stand  in  or  along  any 
railroad,  street,  or  highway  within  the  limits  of  said 
cities  or  their  suburbs  within  300  feet  of  any  inhabited 
dwelling,  and  who  shall  fail,  after  notice  duly  served 
by  this  board,  to  remove  the  same,  shall,  upon  convic- 
tion thereof,  be  fined  not  less  than  five  nor  more  than 

twenty-five  dollars  for  every  such  offense. 

******* 

SEC.  i8^4.  No  person  owning,  occupying  or  hav- 
ing use  of  any  stable,  shed,  pen,  stall,  or  other  place 
within  any  of  the  more  densely  populated  parts  of  the 
District  of  Columbia,  where  animals  of  any  kind  are 
kept  shall  permit  such  stable,  shed,  pen,  stall,  or  place 
to  become  or  to  remain  filthy  or  unwholesome. 

SEC.  1 8  B.  No  person  shall  use  any  stable,  nor 
shall  any  person  having  the  power  and  authority  to 
prevent  permit  any  person  to  use  any  stable,  within 
any  of  the  more  densely  populated  parts  of  the  District 
of  Columbia,  after  the  first  day  of  July,  1907,  unless  the 
surface  of  the  ground  beneath  every  stall  and  for  a 
distance  of  four  feet  from  the  rear  thereof  be  covered 
with  a  water-tight  floor  laid  with  such  grades  as  will 
cause  all  fluids  that  fall  upon  it  to  flow  as  promptly  as 
possible,  if  a  public  sewer  be  available,  into  the  public 
sewer,  and,  if  a  public  sewer  be  not  available,  to  that 
portion  of  the  premises  where  they  will  cause  the  least 
possible  nuisance. 

SEC.  1 8  C.  Every  person  owning  or  occupying  any 
building  or  part  of  a  building  within  any  of  the  more 
densely  populated  parts  of  the  District  of  Columbia, 


APPENDIX  III  287 

where  one  or  more  horses,  mules,  cows,  or  similar  ani- 
mals are  kept,  shall  maintain  in  connection  therewith 
a  bin  or  pit  for  the  reception  of  manure,  and,  pending 
the  removal  from  the  premises  of  the  manure  from 
the  animal  or  animals  aforesaid,  shall  place  such  ma- 
nure in  said  bin  or  pit.  The  bin  or  pit  required  by  this 
regulation  shall  be  located  at  a  point  as  remote  as  prac- 
ticable from  any  dwelling,  church,  school  or  similar 
structure,  owned  or  occupied  by  any  person  or  persons 
in  the  neighborhood  of  said  bin  or  pit,  other  than  the 
owner  or  occupant  of  the  building  or  part  of  building 
aforesaid,  and  as  remote  as  practicable  from  any  pub- 
lic street  or  avenue;  shall  be  so  constructed  as  to  ex- 
clude rain  water,  and  shall  in  all  other  respects  be 
watep-tight  except  as  it  may  be  connected  with  the  pub- 
lic sewer  or  as  other  definite  provision  may  be  made 
for  cleaning  and  flushing  from  time  to  time;  shall  be 
provided  with  a  suitable  cover,  and  constructed  so  as 
to  prevent  in  so  far  as  may  be  practicable  the  ingress 
and  egress  of  flies.  No  bin  or  pit  shall  be  constructed 
the  bottom  of  which  is  below  the  level  of  the  surface 
of  the  surrounding  earth  unless  it  be  of  substantial 
masonry  and  connected  with  the  public  sewer.  The 
provisions  of  this  paragraph  shall  take  effect  from  and 
after  the  expiration  of  three  months  immediately  fol- 
lowing its  promulgation. 

SEC.  i8Z).  No  person  owning  or  occupying  any 
building  or  part  of  a  building  located  within  any  of  the 
more  densely  populated  parts  of  the  District  of  Colum- 
bia, in  which  building  or  part  of  a  building  any  horse, 


288    THE  HOUSE  FLY— DISEASE  CAKRIKR 

mule,  cow,  or  similar  animal  is  kept,  shall  keep  any 
manure,  or  permit  any  manure  to  be  kept,  in  or  upon 
any  portion  of  the  premises  other  than  the  bin  or  pit 
provided  for  that  purpose;  nor  shall  any  person  afore- 
said allow  any  such  bin  or  pit  to  be  overfilled  or  to  be 
needlessly  uncovered. 

SEC.   i8E.     The  provisions  of  paragraphs  C  and  D 
shall  not  apply  to  the  keeping  of  manure  from  horses 
when  such  manure  is  kept  tightly  rammed  into  \\c-ll 
covered  barrels  for  the  purpose  of  removal  in  such  bar- 
rels. 

SEC.  i8F.  No  person  shall  permit  any  manure  to 
accumulate  on  premises  under  his  control  in  such  a 
manner  or  to  such  an  extent  as  to  give  rise  to  objec- 
tionable odors  upon  any  public  highway  or  upon  any 
premises  owned  or  occupied  by  any  person  other  than 
the  person  owning  or  occupying  the  premises  on  which 
said  manure  is  located.  Every  person  having  the  use 
of  any  manure  bin  or  pit  and  every  person  keeping 
manure,  in  any  of  the  more  densely  populated  parts 
of  the  District  of  Columbia,  shall  cause  all  such  ma- 
nure to  be  removed  from  the  premises  at  least  twice 
every  week  between  June  first  and  October  thirty- 
first,  inclusive,  of  each  year,  and  at  least  once 
every  week  between  November  first  of  each  year  and 
May  thirty-first  of  the  following  year,  both  dates  in- 
clusive. 

SEC.  1 8  G.  Every  person  using  within  the  District 
of  Columbia  any  building,  or  any  portion  of  a  building, 
in  the  city  of  Washington,  or  in  any  of  the  more 


APPENDIX  III  289 

densely  populated  suburbs  thereof,  as  a  stable  for  one 
or  more  horses,  mules,  or  cows,  shall  report  that  fact 
to  the  health  officer  in  writing,  within  thirty  days  after 
this  regulation  takes  effect,  giving  his  or  her  name, 
and  the  location  of  such  stable,  and  the  number  and 
the  kind  of  the  animals  stabled  therein ;  and  thereafter 
every  person  occupying  any  building,  or  any  portion 
of  a  building,  in  the  city  of  Washington,  or  in  any  of 
the  more  densely  populated  suburbs  thereof,  for  the 
purpose  aforesaid,  shall  report  in  like  manner  his  or 
her  name  and  the  location  of  said  stable,  and  the  num- 
ber and  kind  of  animals  stabled  therein,  within  five 
days  after  the  beginning  of  his  or  her  occupancy  of 
such  buildings;  provided,  that  stables  recorded  at  the 
Health  Office  as  parts  of  dairy  farms  in  the  District 
of  Columbia  need  not  be  so  reported. 

SEC.  iSH.  No  person  who  has  removed  manure 
from  any  bin  or  pit,  or  any  other  place  where  manure 
has  been  accumulated,  shall  deposit  such  manure  in  any 
place  within  any  of  the  more  densely  populated  parts 
of  the  District  of  Columbia  without  a  permit  from  the 
health  officer  authorizing  him  so  to  do  and  then  only 
in  accordance  with  the  terms  of  such  permit.  The 
provisions  of  this  paragraph  shall  not  apply  to  the  dis- 
tribution of  manure  over  lawns  and  parking  when  such 
manure  has  been  so  thoroughly  rotted  or  decomposed 
that  its  distribution  gives  rise  to  no  offensive  odors  on 
adjacent  properties  or  on  public  thoroughfares. 

SEC.  1 87.  Any  person  violating  any  of  the  pro- 
visions of  this  section  shall  upon  conviction  thereof  be 


290    THE  HOUSE  FLY— DISEASE  CARRIER 

punished  by  a  fine  of  not  more  than  forty  dollars  for 
each  offense. 

Extract  from  Article  IX,  Police  Regulations 

ARTICLE  IX 

SEC.  10.  No  person  shall  remove  or  transport  any 
manure  over  any  public  highway  in  any  of  the  more 
densely  populated  parts  of  the  District  of  Columbia 
except  in  a  tight  vehicle,  which  if  not  enclosed  must 
be  effectually  covered  with  canvas  so  secured  to  the 
sides  and  ends  of  the  vehicle  as  to  prevent  the  manure 
from  being  dropped  while  being  removed,  and  so  as 
to  limit  as  much  as  practicable  the  escape  of  odors  from 
said  manure. 

SEC.  20.  Manure  may  be  deposited  in  pits  below 
the  surface  of  alleys  that  are  not  less  than  fifteen  feet 
wide,  but  the  pit  must  not  extend  more  than  four  feet 
beyond  the  building  line.  The  walls  must  be  substan- 
tial and  water-tight,  with  stone  or  iron  coping,  bedded 
in  cement,  set  fair  with  the  surface  of  the  alley.  They 
must  be  covered  with  heavy  wrought-iron  doors,  flush 
with  the  alley  pavement  or  surface,  sufficiently  strong 
to  carry  heavily  loaded  carts  or  other  vehicles,  and  pro- 
vided with  ventilation  by  means  of  a  flue  inside  of  the 
stable  and  extending  above  the  roof  of  the  same,  and 
they  must  be  drained  by  sewer  connections,  as  directed 
by  the  Inspector  of  Plumbing. 


APPENDIX  III 

EXECUTIVE  OFFICE 

COMMISSIONERS  OF  THE  DISTRICT  OF  COLUMBIA 
ORDERED:  WASHINGTON,  April  11,  1908. 

That,  Pursuant  to  the  authority  vested  in  the  Commis- 
sioners by  the  "Joint  Resolution  authorizing  the  Commis- 
sioners of  the  District  of  Columbia  to  alter,  amend,  or 
repeal  certain  health  ordinances"  approved  February  28, 
1899,  "An  ordinance  to  prevent  the  sale  of  unwholesome 
food  in  the  cities  of  Washington  and  Georgetown"  as 
amended  by  Commissioners'  orders  of  January  2,  1902; 
April  21,  1903 ;  October  6,  1904;  April  24,  1906;  May  31, 
1907,  and  June  10,  1907,  is  hereby  further  amended  by 
inserting  after  the  word  "effectually"  in  section  13  thereof 
the  phrase  "or  effectually  protected  by  a  power-driven  fan 
or  fans,"  so  that  said  section  shall  read  as  follows : 

SEC.  13.  Every  manager  of  a  store,  market,  dairy, 
cafe,  lunch  room,  or  any  other  place  in  the  District  of 
Columbia,  where  a  food,  or  a  beverage,  or  confectionery, 
or  any  similar  article,  is  manufactured  or  prepared  for 
sale,  stored  for  sale,  offered  for  sale,  or  sold,  shall  cause 
it  to  be  screened  effectually,  or  effectually  protected  by 
power-driven  fan  or  fans,  so  as  to  prevent  flies  and  other 
insects  from  obtaining  access  to  such  food,  beverage, 
confectionery,  or  other  article,  and  shall  keep  such  food, 
beverage,  confectionery,  or  other  article  free  from  flies 
and  other  insects  at  all  times.  Any  person  violating  the 
provisions  of  this  regulation  shall,  upon  conviction 
thereof,  be  punished  by  a  fine  of  not  more  than  twenty- 
five  dollars  for  each  and  every  such  offense.  This  regu- 
lation shall  take  effect  from  and  after  the  expiration  of 
thirty  days  immediately  following  the  date  of  its  promul- 
gation. 

Official  copy  furnished  Health  Department. 
By  order: 

WM.  TINDALL,    Secretary. 

Officially  published  in  the  Washington  Herald  April 
1 6,  1908. 


292    THE  HOUSE  FLY— DISEASE  CARRIER 

EXECUTIVE  DEPARTMENT 

COMMISSIONERS  OF  THE  DISTRICT  OF  COLUMBIA 
• 

WASHINGTON,  December  i,  1909. 
ORDERED  : 

That  Section  60  of  "An  Ordinance  to  prevent  the  sale 
of  unwholesome  food  in  the  cities  of  Washington  and 
Georgetown"  as  amended  by  orders  of  the  Commissioners 
of  the  District  of  Columbia,  be,  and  the  same  is  hereby 
amended  so  as  to  read  as  follows : 

SEC.  60.  No  person  shall  expose  for  sale  on  any  pub- 
lic highway  or  in  any  uninclosed  market,  store,  shop, 
stand,  or  stall,  or  in  any  open  lot,  or  transport  over  any 
public  highway  to  any  place  for  sale  there  or  elsewhere, 
in  the  District  of  Columbia,  any  meat,  fish,  plucked 
poultry  or  game  bird,  dressed  rabbit  or  squirrel,  butter, 
butterine,  oleomargarine,  lard,  lard  compound  or  sub- 
stitute, cheese,  candy,  cake,  bread,  dates,  figs,  or  any 
food  whatsoever  of  a  kind  not  commonly  washed,  peeled, 
shelled  or  cooked,  before  eaten,  unless  the  same  be  then 
and  there  effectually  and  in  a  cleanly  manner  wrapped, 
or  covered  and  enclosed,  so  as  to  protect  it  from  dust  and 
insects. 

No  person  shall  expose  for  sale  in  any  place  aforesaid 
between  April  ist  and  October  3ist,  inclusive,  of  any 
year,  any  fresh  meat  or  fresh  fish  unless  said  meat  or  fish, 
while  thus  exposed,  be  kept  at  a  temperature  not  exceed- 
ing fifty-five  degrees  Fahrenheit. 

Official  copy  furnished. 
By  order : 

WM.  TINDALL, 

Secretary. 

Officially  published  in  the  Washington  Post,  December 
3,  1909- 


APPENDIX  IV 
DIRECTIONS  FOR  BUILDING  A  SANITARY  PRIVY* 

IN  order  to  put  the  construction  of  a  sanitary  privy 
for  the  home  within  the  carpentering  abilities  of 
boys,  a  practical  carpenter  has  been  requested  to  con- 
struct models  to  conform  to  the  general  ideas  expressed 
in  this  article,  and  to  furnish  estimates  of  the  amount 
of  lumber,  hardware,  and  wire  screening  required. 
Drawings  of  these  models  have  been  made  during  the 
process  of  construction  (Figs.  36,  37)  and  in  completed 
condition  (Figs.  38,  39).  The  carpenter  was  requested 
to  hold  constantly  in  mind  two  points,  namely,  (i) 
economy  and  (2)  simplicity  of  construction.  It  is  be- 
lieved that  any  fourteen-year-old  schoolboy  of  average 
intelligence  and  mechanical  ingenuity  can,  by  follow- 
ing these  plans,  build  a  sanitary  privy  for  his  home  at 
an  expense  for  building  materials,  exclusive  of  recep- 
tacle, of  five  to  ten  dollars,  according  to  locality.  It  is 
further  believed  that  the  plans  submitted  cover  the  es- 
sential points  to  be  considered.  They  can  be  elaborated 
to  suit  the  individual  taste  of  persons  who  prefer  a 
more  elegant  and  more  expensive  structure.  For  in- 
stance, the  roof  can  have  a  double  instead  of  a  single 
slant,  and  can  be  shingled ;  the  sides,  front,  and  back 
can  be  clapboarded  or  they  can  be  shingled.  Instead 

Taken  from  Public  Health  Bull.  No.  37,  U.  S.  Public  Health 
and  Marine  Hospital  Service.  By  C  W.  Stiles,  Ph.D.,  Washing- 
ton, 1910. 

293 


294    THE  HOUSE  FLY— DISEASE  CARRIER 

of  one  seat  or  six  seats,  there  may  be  two,  three,  four, 
or  five  seats,  etc.,  according  to  necessity. 

A  SINGLE-SEATED  PRIVY  FOR  THE  HOME 

Nearly  all  privies  for  the  home  have  seats  for  two 
persons,  but  a  single  privy  can  be  made  more  econom- 
ically. 

Framework  (Fig.  36). — The  lumber  required  for 
the  framework  (Fig.  37)  of  the  outhouse  shown  as 
completed  in  Fig.  38  is  as  follows: 

A.  Two  pieces  of  lumber  (scantling)  4  feet  long  and  6 

inches  square  at  ends. 

B.  One  piece  of  lumber  (scantling)  3  feet  10  inches  long; 

4  inches  square  at  ends. 

C.  Two  pieces  of  lumber  (scantling)  3  feet  4  inches  long; 

4  inches  square  at  ends. 

D.  Two  pieces  of  lumber  (scantling)  7  feet  9  inches  long; 

2  by  4  inches  at  ends. 

E.  Two  pieces  of  lumber  (scantling)  6  feet  7  inches  long; 

2  by  4  inches  at  ends. 

F.  Two  pieces  of  lumber  (scantling)  6  feet  3  inches  long; 

2  by  4  inches  at  ends. 

G.  Two  pieces  of  lumber  (scantling)  5  feet  long;  2  by  4 

inches  at  ends. 
H.  One  piece  of  lumber   (scantling)    3   feet   10  inches 

long ;  2  by  4  inches  at  ends. 
/.  Two  pieces  of  lumber  (scantling)  3  feet  4  inches  long; 

2  by  4  inches  at  ends. 
/.  Two  pieces  of  lumber  (scantling)  3  inches  long;  2  by 

4  inches  at  ends. 
K.  Two  pieces  of  lumber    (scantling)   4   feet   7   inches 

long;  6  inches  wide  by  I  inch  thick.    The  ends  of 

K  should  be  trimmed  after  being  nailed  in  place. 
L.  Two  pieces  of  lumber  (scantling)  4  feet  long;  6  inches 

wide,  and  I  inch  thick. 


APPENDIX  IV 


295 


1 


\ 


1! 


\ 


\ 


296    THE  HOUSE  FLY— DISEASE  CARRIER 

First  lay  down  the  sills  marked  A  and  join  them 
with  the  joist  marked  B;  then  nail  in  position  the  two 
joists  marked  C,  with  their  ends  3  inches  from  the 
outer  edge  of  A;  raise  the  corner  posts  (D  and  F), 
spiking  them  at  bottom  to  A  and  C,  and  joining  them 
with  L,  1 2,  G,  and  K;  raise  door  posts  E,  fastening 
them  at  /,  and  then  spike  7X  in  position ;  H  is  fastened 
to  K.  (Fig.  37.) 

Sides. — Each  side  requires  four  boards  (a)  12  inches 
wide  by  i  inch  thick  and  8  feet  6  inches  long;  these  are 
nailed  to  K,  L,  and  A.  (Fig.  37.)  The  corner  boards 
are  notched  at  G,  allowing  them  to  pass  to  bottom  or 
roof;  draw  a  slant  from  front  to  back  at  G-G,  on  the 
outside  of  the  boards,  and  saw  the  four  side  boards 
to  correspond  with  this  slant.  (Fig.  39.) 

Back. — The  back  requires  two  boards  (b)  12  inches 
wide  by  i  inch  thick  and  6  feet  1 1  inches  long,  and  two 
boards  12  inches  wide  by  i  inch  thick  and  6  feet  5 
inches  long.  The  two  longest  boards  (b)  are  nailed 
next  to  the  sides ;  the  shorter  boards  are  each  sawed  in 
two  so  that  one  piece  (c1)  measures  4  feet  6  inches, 
the  other  (c2)  i  foot  n  inches;  the  longer  portion 
(c1)  is  nailed  in  position  above  the  seat;  the  shorter 
portion  (c2)  is  utilized  in  making  the  back  door. 

Floor. — The  floor  requires  four  boards  (d)  which 
(when  cut  to  fit)  measure  I  inch  thick,  12  inches  wide, 
and  3  feet  10  inches  long.  (Fig.  38.) 

Front. — The  front  boards  may  next  be  nailed  on. 
The  front  requires  (aside  from  the  door)  two  boards 
(E)  which  (when  cut  to  fit)  measure  i  inch  thick,  9 


APPENDIX  IV 


297 


37-— The  framework  for  a  single-seated  privy.     (Redrawn 
from  Stiles.) 


298    THE  HOUSE  FLY— DISEASE  CARRIER 

inches  wide,  and  8  feet  5  inches  long;  these  are  nailed 
next  to  the  sides.  (Fig.  38.) 

Roof. — The  roof  may  now  be  finished.  This  re- 
quires five  boards  (/),  measuring  (when  cut  to  fit) 
i  inch  thick,  12  inches  wide,  and  6  feet  long.  They 
are  so  placed  that  they  extend  8  inches  beyond  the  front. 
The  joints  (cracks)  are  to  be  broken  (covered)  by 
laths  one-half  inch  thick,  3  inches  broad,  and  6  feet 
long.  (Fig.  39.) 

Box. — The  front  of  the  box  may  be  made  with 
two  boards,  i  inch  thick,  3  feet  10  inches  long.  One 
may  measure  12  inches  wide,  the  other  5  inches  wide. 
These  are  nailed  in  place,  so  that  the  back  of  the 
boards  is  18  inches  from  the  inside  of  the  back- 
boards. The  seat  of  the  box  may  be  made  with  two 
boards,  I  inch  thick,  3  feet  10  inches  long;  one 
may  measure  12  inches  wide,  the  other  7  inches 
wide.  One  must  be  jogged  (cut  out)  to  fit  around  the 
back  corner  posts  (F).  An  oblong  hole,  10  inches 
long  and  7^2  inches  wide,  is  cut  in  the  seat.  The  edge 
should  be  smoothly  rounded  or  beveled.  An  extra 
(removable)  seat  for  children  may  be  made  by  cutting 
a  board  I  inch  thick,  15  inches  wide,  and  20  inches 
long;  in  this  seat  a  hole  is  cut,  measuring  7  inches  long 
by  6  inches  wide ;  the  front  margin  of  this  hole  should 
be  about  3  inches  from  the  front  edge  of  the  board; 
to  prevent  warping,  a  cross  cleat  is  nailed  on  top  near 
or  at  each  end  of  the  board. 

A  cover  (K)  to  the  seat  should  measure  i  inch  thick 
by  15  inches  wide  by  20  inches  long;  it  is  cleated  on 


APPENDIX  IV 


Fig.  38. — Front  view  of  single-seated  sanitary  privy.     (Redrawn 
from  Stiles.) 


300    THE  HOUSE  FLY— DISEASE  CARRIER 

top  near  the  ends,  to  prevent  warping;  it  is  hinged  in 
back  to  a  strip  i  inch  thick,  3  inches  wide,  and  20 
inches  long,  which  is  fastened  to  the  seat.  Cleats 
may  also  be  nailed  on  the  seat  at  the  sides  of  the  cover. 
On  the  inside  of  the  backboard,  12  inches  above  the 
seat,  there  should  be  nailed  a  block  ( i ) ,  2  inches  wide, 
6  inches  long,  extending  forward  3*4  inches;  this  is 
intended  to  prevent  the  cover  from  falling  backward 
and  to  make  it  to  fall  down  over  the  hole  when  the 
occupant  rises. 

On  the  floor  of  the  box  (underneath  the  seat)  two 
or  three  cleats  are  nailed  in  such  a  position  that 
they  will  always  center  the  tub;  the  position  of  these 
cleats  depends  upon  the  size  of  the  tub. 

Back  door. — In  making  the  back  of  the  privy  the 
two  center  boards  were  sawed  at  the  height  of  the 
bottom  of  the  seat.  The  small  portions  (c2)  sawed 
off  (23  inches  long)  are  cleated  (O)  together  so 
as  to  form  a  back  door  which  is  hinged  above;  a 
bolt  or  a  button  is  sufficient  arrangement  to  keep  the 
door  closed. 

Front  door. — The  front  door,  Fig.  38,  is  made  by 
cleating  (/>)  together  three  boards  (Q)  i  inch  thick, 
10  inches  wide,  and  (when  finished)  6  feet  7  inches 
long;  it  is  best  to  use  three  cross-cleats  (/>)  (i  inch 
thick,  6  inches  wide,  30  inches  long),  placed  on  the 
inside.  The  door  is  hung  with  two  hinges  (6-inch 
"strap"  hinges  will  do),  which  are  placed  on  the  right 
as  one  faces  the  privy,  so  that  the  door  opens  from 
the  left.  The  door  should  close  with  a  coil  spring  (cost 


APPENDIX  IV 


301 


about  10  cents)  or  with  a  rope  and  weight,  and  may 
fasten  on  the  "inside  with  a  catch  or  a  cord.     Under 


Fig.   39- — Rear  view  of  single-seated  sanitary  privy.     (Redrawn 
from  Stiles.) 

the  door  a  crosspiece  (R)  i  inch  thick,  4  inches  wide, 
30  inches  long  (when  finished)  may  be  nailed  to  the 


302    THE  HOUSE  FLY— DISEASE  CARRIER 

joist.  Stops  may  be  placed  inside  the  door.  These 
should  be  i  inch  thick,  3  inches  wide,  and  6  feet  6 
inches  long,  and  should  be  jogged  (that  is  to  say,  cut 
out)  to  fit  the  cross-cleats  (/>)  on  the  door.  Close  over 
the  top  of  the  door  place  a  strip  i  inch  thick,  2  inches 
wide,  30  inches  long,  nailed  to  I.  (Fig.  37).  A  corre- 
sponding piece  is  placed  higher  up  directly  under  the 
roof,  nailed  to  G.  A  strap  or  door-pull  is  fastened 
to  the  outside  of  the  door. 

Ventilators. — There  should  be  five  ventilators  (w). 
One  is  placed  at  each  side  of  the  box  directly  under  the 
seat;  it  measures  6  to  8  inches  square.  Another  (12 
inches  square)  is  placed  near  the  top  on  each  side  of 
the  privy.  A  fifth  (30  inches  long  Sl/2  inches  wide)  is 
placed  over  the  door,  between  G  and  I  (Figs.  37,  38). 
The  ventilators  are  made  of  15-mesh  copper  wire, 
which  is  first  tacked  in  place  and  then  protected  at  the 
edge  with  the  same  kind  of  lath  that  is  used  on  the 
cracks  and  joints. 

Lath. — Outside  cracks  (joints)  are  covered  with 
lath  one-half  inch  thick  by  3  inches  wide. 

Receptacle. — For  a  receptacle,  saw  a  water-tight  bar- 
rel to  fit  snugly  under  the  seat;  or  purchase  a  can  or 
tub,  as  deep  (17  inches)  as  the  distance  from  the  un- 
der surface  of  the  seat  to  the  floor.  If  it  is  not  pos- 
sible to  obtain  a  tub,  barrel,  or  can  of  the  desired  size, 
the  receptacle  used  should  be  elevated  from  the  floor 
by  blocks  or  boards  so  that  it  fits  snugly  under  the  seat. 
A  galvanized  can  measuring  16  inches  deep  and  16 
inches  in  diameter  can  be  purchased  for  about  $i,  or 


APPENDIX  IV  303 

even  less.     An  empty  candy  bucket  can  be  purchased 
for  about  10  cents. 

Order  for  material. — The  carpenter  has  made  out  the 
following  order  for  lumber  (pine,  No.  i  grade)  and 
hardware  to  be  used  in  building  a  privy  such  as  has 
been  described : 

i  piece  scantling,  6  by  6  inches  by  8  feet  long,  24  square 
feet. 

1  piece  scantling,  4  by  4  inches  by  12  feet  long,  i6"square 

feet. 

5  pieces  scantling,  2  by  4  inches  by   16  feet  long,  54 

square  feet. 

3  pieces  board,  i  by  6  inches  by  16  feet  long,  24  square 
feet. 

2  pieces  board,  i  by  9  inches  by  9  feet  long,  14  square 

feet. 

3  pieces  board,  i  by  10  inches  by  7  feet  long,  18  square 

feet. 
15  pieces  board,  i  by  12  inches  by  12  feet  long,  180  square 

feet. 
12  pieces  board,  /^  by  3  inches  by  16  feet  long,  48  square 

feet. 
2  pounds  of  2O-penny  spikes. 

6  pounds  of  lo-penny  nails. 
2  pounds  of  6-penny  nails. 

7  feet  screen,  I5~mesh,  copper,  12  inches  wide. 

4  hinges,  6-inch  "strap,"  for  front  and  back  doors. 
2  hinges,  6-inch  "T,"  or  3-inch  "butts,"  for  cover. 
i  coil  spring  for  front  door. 

According  to  the  carpenter's  estimate,  these  materials 
will  cost  from  $5  to  $10,  according  to  locality. 

There  is  some  variation  in  the  size  of  lumber,  as  the 
pieces  are  not  absolutely  uniform.  The  sizes  given  in 


304    THE  HOUSE  FLY— DISEASE  CARRIER 

the  lumber  order  represent  the  standard  sizes  which 
should  be  ordered,  but  the  purchaser  need  not  expect 
to  find  that  the  pieces  delivered  correspond  with  mathe- 
matical exactness  to  the  sizes  called  for.  On  this  ac- 
count the  pieces  must  be  measured  and  cut  to  measure 
as  they  are  put  together. 

ESTIMATE  OF  MATERIAL  FOR  SCHOOL  PRIVY 

The  following  estimate  of  building  materials  has 
been  made  by  a  carpenter  for  the  construction  of  a 
six-seated  school  privy.  The  estimated  cost  of  these 
materials  is  $25  to  $50,  according  to  locality ;  this  does 
not  include  the  pails,  which  ought  not  to  cost  over  $i 
apiece. 

3  pieces  scantling,  6  by  6  inches  by  20  feet,  180  square 

feet. 
I  piece   scantling,  6  by  6  inches  by  8   feet,  24   square 

inches. 

Scantling,  2  by  4  inches,  165  square  feet. 
Boards,  I  by  12  inches,  600  square  feet. 
Boards,  I  by  10  inches,  185  square  feet. 
Boards,  I  by  8  inches,  100  square  feet. 
Boards,  I  by  6  inches,  80  square  feet. 
Boards,  l/2  by  3  inches,  100  square  feet. 
Flooring,  80  square  feet. 

40  feet  15-mesh  copper  wire  screen,  12  inches  wide. 
12  pairs  of  hinges,  6-inch  "strap." 

6  pairs  of  hinges,  6-inch  "T." 

3  pounds  of  2O-penny  spikes. 
15  pounds  of  lo-penny  nails. 

8  pounds  of  6-penny  nails. 

6  coil  springs  for  front  doors. 

6  knobs  or  latches. 


APPENDIX  V 

A  SIMPLE  APPARATUS  FOR  USE  IN  THE  SAFE 
DISPOSAL  OF  NIGHT-SOIL* 


proper  disposal  of  human  excreta  is  recog- 
1  nized  by  sanitarians  as  the  most  important  single 
measure  needed  to  prevent  the  spread  of  typhoid  fever, 
hookworm  disease,  the  dysenteries,  and  certain  other 
widely  prevalent  diseases. 

Where  large  numbers  of  people  are  gathered  to- 
gether, as  in  cities,  the  removal  of  dejecta  from  per- 
sons becomes,  from  an  esthetic  standpoint  at  least,  a 
necessity,  and  practically  all  modern  cities  have  ex- 
pended large  sums  of  money  to  install  sewerage  sys- 
tems, which,  though  usually  removing  the  sewage  in 
such  a  way  as  to  prevent  it  from  becoming  an  intoler- 
able nuisance  to  sight  and  smell,  yet  frequently  fall 
short  of  safety  from  a  sanitary  standpoint. 

Though  a  city  may  dispose  of  its  own  sewage  prop- 
erly, its  people  are  exposed  to  excreta-borne  infections 
brought  in  on  various  food  supplies  from  farms.  Thus 
the  sanitation  of  the  farm  is  vastly  important,  not  only 
to  the  rural  population,  but  also  to  the  urban,  and  there- 
fore the  farm  as  the  fountain  head  of  various  and  far- 
flowing  streams  of  infection  is  the  logical  point  to 

*From  Public  Health  Report  No.  54.  Preliminary  Note  on  a 
Simple  and  Inexpensive  Apparatus  in  Use  in  Safe  Disposal  of 
Night-Soil.  By  L.  L.  Lumsden,  Norman  Roberts,  and  Ch  War- 
dell  Stiles. 

305 


306    THE  HOUSE  FLY— DISEASE  CARRIER 

attack  in  campaigns  of  prevention  against  many  of  the 
communicable  diseases.* 

Among  the  obstacles  in  progress  in  farm  sanitation 
one  of  the  chief  has  been  the  difficulty  of  convincing 
the  farmer  that  the  benefits  which  would  accrue  from 
proper  disposal  of  excreta  would  justify  the  expense 
of  constructing,  and  the  disagreeable  labor  of  main- 
taining, the  sanitary  devices  proposed.  Therefore, 
whatever  can  be  done  in  simplification  and  in  lessen- 
ing expense  and  labor  in  the  installation  and  mainte- 
nance of  an  efficient  disposal  system  will  increase  the 
chances  of  its  adoption. 

The  apparatus  described  in  this  note  has  been  in  use 
in  one  of  the  work  rooms  of  the  Hygienic  Laboratory 
since  July  12,  1910.  It  has  been  seen  by  a  number  of 
sanitarians  from  different  sections  of  the  country,  and 
several  of  them  have  expressed  a  desire  to  test  it  for 
themselves.  The  details  of  construction  are  presented 
at  this  time  in  order  to  place  them  at  the  disposal  of  any 
persons  who  may  desire  to  test  the  apparatus  in  ques- 
tion. 

Starting  point  of  studies. — Starting  out  on  the  prin- 
ciple that  the  forces  of  nature  in  fermentation  should, 
if  possible,  be  utilized,  we  have  sought  to  meet  the  ob- 
jections that  have  thus  far  occurred  to  us  in  respect  to 
the  wet  system.  Further,  the  importance  of  economy 
and  of  simplicity  of  construction  has  been  constantly 
held  in  mind.  An  effort  has  also  been  made  to  reduce 

*Freeman,  Allen  W.,  The  Farm  the  Next  Point  of  Attack  in 
Sanitary  Progress.  Jour.  A.  M.  A.,  August  27,  1910. 


APPENDIX  V 


307 


to  a  minimum  the  labor  and  skill  involved  in  taking 
care  of  the  privy,  and,  finally,  while  sanitary  safety  has 
been  the  chief  object  in  mind,  we  have  not  ignored  the 
widespread  demand  that  human  excreta  be  turned  to 
economic  account. 


Fig.  40. — The  Lumsden,   Roberts   and    Stiles   apparatus   for  the 

safe  disposal  of  night-soil.     (Redrawn  from  Lumsden, 

Roberts  and  Stiles.) 


308    THE  HOUSE  FLY— DISEASE  CARRIER 

Construction. — The  apparatus  under  consideration 
consists  of  the  following  parts : 

1.  A  water-tight  barrel,  to  be  used  as  a  liquefier. 

2.  A  covered  water-tight  barrel,  can,  or  other  con- 
tainer to  receive  the  effluent. 

3.  A  connecting.pipe  about  two  and  one-half  inches 
in  diameter,  about  twelve  inches  long,  and  provided 
with  an  open  "T"  at  one  end,  both  openings  of  the 
"T"  being  covered  by  wire  screens. 

4.  A  tight  box,  preferably  zinc  lined,  which  fits 
tightly  on  the  top  of  the  liquefying  barrel ;  it  is  pro- 
vided with  an  opening  on  top  for  the  seat,  which  has 
an  automatically  closing  lid. 

5.  An  anti-splashing  device  consisting  of  a  small 
board  placed  horizontally  under  the  seat  and  one 
inch  below  the  level  of  the  transverse  connecting 
pipe;   it  is  held  in  place   by  a  rod,   which   passes 
through  eyes  or  rings  fastened  to  the  box,  and  by 
which  the  board  is  raised  and  lowered.    The  liquefy- 
ing tank  is  filled  with  water  up  to  the  point  where  it 
begins  to  trickle  into  the  effluent  tank. 

As  an  insect  repellent  a  thin  film  of  some  form  of 
petroleum  may  be  poured  on  the  surface  of  the  liquid 
in  each  barrel. 

Practical  ivorking  of  the  apparatus. — When  the 
privy  is  to  be  used,  the  rod  is  pulled  up  so  that  the  anti- 
splashing  board  rises  to  within  about  one  inch  below 
the  surface  of  the  water.  The  fecal  matter  falls  into 
the  water,  but  this  board  prevents  splashing,  and  thus 
meets  one  of  the  greatest  objections  thus  far  raised  to 
the  wet  system.  After  defecation  the  person  sinks  the 
anti-splashing  board  by  depressing  the  rod,  and  the 


APPENDIX  V  309 

fecal  matter  then  floats  free  into  the  water.  We  are 
now  working  on  an  improvement  whereby  the  rod  will 
connect  with  the  automatically  closing  lid,  and  the  anti- 
splashing  board  will  rise  and  sink  as  the  lid  is  opened 
and  closed. 

Although  some  of  the  fecal  matter  floats,  it  is  pro- 
tected both  from  fly  breeding  and  fly  feeding  in  the 
following  ways :  First,  by  the  automatically  closing  lid ; 
second,  by  the  water;  third,  by  the  film  of  oil;  and, 
fourth,  for  additional  safety,  the  apparatus  should  be 
located  in  a  screened  place.  The  film  of  oil  also  pre- 
vents the  breeding  of  mosquitoes  in  the  barrel.  Ac- 
cordingly, so  far  as  the  privy  as  a  breeding  or  feed- 
ing place  for  flies  and  mosquitoes  is  concerned,  the 
model  in  question  completely  solves  the  problem. 

The  fecal  material  becomes  fermented  in  the  water 
and  gradually  liquefies ;  the  addition  of  excreta  natu- 
rally raises  the  level  of  the  liquid,  and  the  excess  flows 
into  the  effluent  tank,  where  it  is  protected  from  in- 
sects by  the  cover  and  by  the  film  of  oil.  This  effluent 
may  be  allowed  to  collect  in  the  tank  until  it  reaches  the 
level  of  the  connecting  pipe,  when  it  may  be  safely  dis- 
posed of  in  various  ways  to  be  discussed  later. 

From  July  I2th  to  October  26th  there  have  been 
246  defecations  (with  urination)  into  the  model  in 
question,  making  about  two  and  one-third  defecations 
a  day.  The  effluent  has  amounted  to  about  twelve  gal- 
lons of  manageable  fluid.  It  has  not  been  found  neces- 
sary to  add  water  to  the  liquefying  barrel  since  the  ap- 
paratus was  put  into  operation. 


310    THE  HOUSE  FLY— DISEASE  CARRIER 

Although  the  period  in  question  included  the  hottest 
part  of  summer,  the  odor,  when  compared  with  that  of 
the  average  privy,  has  been  negligible. 

It  is  thus  seen  that  this  device  appears  to  meet  the 
following  requirements : 

1.  It  solves  the  fly  and  mosquito  problems,  so  far 
as  the  privy  is  concerned. 

2.  It  liquefies  fecal  matter  and  reduces  its  volume 
so  that  it  may  be  safely  disposed  of  more  easily  and 
cheaply  than  night-soil. 

4.  It  reduces  odor. 

4.  It  reduces  the  labor  of  cleaning  the  privy  and 
makes  this  work  less  disagreeable. 

5.  It  is  of  simple  and  inexpensive  construction. 

The  effect  of  the  fermentative  changes  in  the  ap- 
paratus upon  the  viability  of  typhoid  bacilli  and  hook- 
worm eggs  has  not  been  determined,  but  other  experi- 
ments tend  to  show  that  under  such  conditions  the  vast 
majority  of  typhoid  bacilli  and  of  hookworm  eggs  in- 
troduced would  die  within  six  weeks'  to  two  months' 
time.  While  the  time  of  storage  can  be  prolonged  ac- 
cording to  the  capacity  of  vessels  provided  for  the  pur- 
pose, we  believe  at  present  that  it  is  safer  and  more 
practical  not  to  depend  upon  storage  alone  to  destroy 
infectious  organisms  in  the  effluent,  but  to  consider  the 
effluent  infectious  and  to  dispose  of  it  accordingly. 

Disposal  of  effluent. — ( i )  Heat :  If  a  suitable  (metal- 
lic) vessel  is  provided  to  receive  the  effluent,  a  fire  may 
be  built  under  the  vessel  and  the  effluent  heated  to  boil- 
ing. Or  if  a  wooden  or  concrete  effluent  tank  is  used, 


APPENDIX  V  311 

the  effluent  may  be  transferred  to  some  other  vessel 
for  boiling. 

After  boiling,  the  fluid  may  be  safely  used  for  fer- 
tilizer under  any  conditions. 

Heat  disinfection  is  the  only  measure  which  can  to- 
day be  recommended  unreservedly. 

(2)  Burial:   Burial  wilt  unquestionably  decrease  the 
dangers  of  spreading  infection,  but  in  the  present  state 
of  our  knowledge  this  method  of  disposal  cannot  be 
relied  upon  as  safe.     If  burial  of  the  effluent  is  prac- 
tised, the  fluid  should  be  disposed  of  not  less  than  300 
feet  from  and  downhill  from  any  neighboring  water 
supply  and  not  less  than  two  feet  underground,  and 
then  only  provided  the  soil  itself  is  a  good  filter.     Bur- 
ial in  a  limestone  region  may  contaminate  water  sup- 
plies miles  away. 

(3)  Chemical  disinfection:    Chemical  disinfectants, 
such  as  chlorinated  lime  and  certain  coal-tar  deriva- 
tives, have  the  great  advantage  of  cheapness  and  can 
be  relied  upon  to  destroy  pathogenic  bacteria.     Our 
knowledge  regarding  the  action  of  chemical  disinfec- 
tants upon  the  eggs  and  spores  of  the  various  animal 
parasites  is  at  present  very  rudimentary,  but  so  far  as 
results  are  known,  their  practicable  use  does  not  seem 
to  be  so  efficient  in  the  destruction  of  the  zooparasitic 
as  of  the  bacterial  infectious  organisms.     Therefore, 
pending  further  investigations,  the  use  of  chemically 
treated  excrement  as  fertilizer  should  not  be  regarded 
as  unqualifiedly  safe. 

(4)  Chemical  disinfection  with  subsequent  burial : 


THE  HOUSE  FLY— DISEASE  CARRIER 

Inasmuch  as  chemical  disinfection  can  be  relied  upon 
to  destroy  pathogenic  bacteria,  and  inasmuch  as  burial 
greatly  reduces  the  danger  from  animal  parasites,  a 
suitable  combination  of  the  two  methods  (chemical  dis- 
infection and  burial)  can  be  used  with  reasonable  safety. 

(5)  Sewers:  In  partly  sewered  towns,  the  effluent 
from  these  privies  may  be  emptied  into  the  sewers.  If 
conditions  are  such  that  the  addition  of  this  material 
to  the  sewage  is  dangerous,  then  the  entire  sewerage 
system  needs  correction. 

Paper. — Only  toilet  paper  so  far  has  been  used,  and 
the  septic  action  seems  to  digest  it.  Other  experiments 
indicate  that  newspaper  would  be  disposed  of  by  septic 
action  in  the  tank,  but  perhaps  some  increase  in  the 
size  of  the  tank  would  be  required. 

Cleaning. — Although  no  water  has  been  added  since 
the  model  was  put  into  operation,  the  contents  of  the 
liquefying  tank  have  remained  fluid,  and  it  is  prob- 
able that  in  a  tank  having  the  capacity  of  an  oil  bar- 
rel, the  amount  of  sludge  from  the  dejecta  of  a  family 
of  five  people  would  not  be  sufficient  to  require  the 
cleaning  of  the  liquefying  tank  oftener  than  once  in 
six  months  to  a  year. 


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